Endangered and Threatened Wildlife and Plants; Endangered Species Status for Sierra Nevada Yellow-Legged Frog and Northern Distinct Population…
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Endangered and Threatened Wildlife and Plants; Endangered Species Status for Sierra Nevada Yellow-Legged Frog and Northern Distinct Population Segment of the Mountain Yellow-Legged Frog, and Threatened Species Status for Yosemite Toad
Final rule.
CFR Part: "50 CFR Part 17"
RIN Number: "RIN 1018-AZ21"
Citation: "79 FR 24256"
Document Number: "Docket No. FWS-R8-ES-2012-0100; 4500030113"
"Rules and Regulations"
SUMMARY: We, the
DATES: This rule becomes effective
ADDRESSES: This final rule is available on the Internet at http://www.regulations.gov and at the Sacramento Fish and Wildlife Office. Comments and materials we received, as well as supporting documentation used in preparing this rule, are available for public inspection at http://www.regulations.gov. All of the comments, materials, and documentation that we considered in this rulemaking are available by appointment, during normal business hours at:
FOR FURTHER INFORMATION CONTACT:
SUPPLEMENTARY INFORMATION:
Executive Summary
Why we need to publish a rule. Under the Endangered Species Act, a species may warrant protection through listing if it is endangered or threatened throughout all or a significant portion of its range. Listing a species as an endangered or threatened species can be only completed by issuing a rule.
This rule will finalize the listing of the
The basis for our action. Under the Endangered Species Act, we can determine that a species is an endangered or threatened species based on any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) Overutilization for commercial, recreational, scientific, or educational purposes; (C) Disease or predation; (D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence.
We have determined that both the
We have also determined that the
Peer review and public comment. We sought comments from independent specialists to ensure that our designations are based on scientifically sound data, assumptions, and analyses. We invited these peer reviewers to comment on our listing proposal. We also considered all comments and information received during the comment period.
Previous Federal Actions
Please refer to the proposed listing rule for the
We will also be finalizing critical habitat designations for the
Summary of Biological Status and Threats for the Sierra Nevada Yellow-Legged Frog and the Northern DPS of the Mountain Yellow-Legged Frog
Background
Please refer to the proposed listing rule for the
Taxonomy
Please refer to the proposed listing rule for the
Vredenburg et al. (2007, p. 371) determined that Rana sierrae occurs in the
For purposes of this rule, we recognize the species differentiation as presented in Vredenburg et al. (2007, p. 371) and adopted by the official societies mentioned above (Crother et al. 2008, p. 11), and in this final rule we refer to Rana sierrae as the
BILLING CODE 4310-55-P
See Illustration in Original Document.
BILLING CODE 4310-55-C
Many studies cited in the rest of this document include articles and reports that were published prior to the official species reclassification, where the researchers may reference either one or both species. Where possible and appropriate, information will be referenced specifically (either as
Species Description
Please refer to the proposed listing rule for the
The belly and undersurfaces of the hind limbs are yellow or orange, and this pigmentation may extend forward from the abdomen to the forelimbs (Wright and Wright 1949, pp. 424-429; Stebbins 2003, p. 233). Mountain yellow-legged frogs may produce a distinctive mink or garlic-like odor when disturbed (Wright and Wright 1949, p. 432; Stebbins 2003, p. 233). Although these species lack vocal sacs, they can vocalize in or out of water, producing what has been described as a faint clicking sound (Zweifel 1955, p. 234; Ziesmer 1997, pp. 46-47; Stebbins 2003, p. 233). Mountain yellow-legged frogs have smoother skin, generally with heavier spotting and mottling dorsally, darker toe tips (Zweifel 1955, p. 234), and more opaque ventral coloration (Stebbins 2003, p. 233) than the foothill yellow-legged frog.
The Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog are similar morphologically and behaviorally (hence their shared taxonomic designation until recently). However, these two species can be distinguished from each other physically by the ratio of the lower leg (fibulotibia) length to snout vent length. The northern DPS of the mountain yellow-legged frog has longer limbs (Vredenburg et al. 2007, p. 368). Typically, this ratio is greater than or equal to 0.55 in the northern DPS of the mountain yellow-legged frog and less than 0.55 in the
Mountain yellow-legged frogs deposit their eggs in globular clumps, which are often somewhat flattened and roughly 2.5 to 5 centimeters (cm) (1 to 2 in) in diameter (Stebbins 2003, p. 444). When eggs are close to hatching, egg mass volume averages 198 cubic cm (78 cubic in) (Pope 1999, p. 30). Eggs have three firm, jelly-like, transparent envelopes surrounding a grey-tan or black vitelline (egg yolk) capsule (Wright and Wright 1949, pp. 431-433). Clutch size varies from 15 to 350 eggs per egg mass (Livezey and Wright 1945, p. 703; Vredenburg et al. 2005, p. 565). Egg development is temperature dependent. In laboratory breeding experiments, egg hatching time ranged from 18 to 21 days at temperatures of 5 to 13.5 degrees Celsius ( [degrees] C) (41 to 56 degrees Fahrenheit ( [degrees] F)) (Zweifel 1955, pp. 262-264). Field observations show similar results (Pope 1999, p. 31).
The tadpoles of mountain yellow-legged frogs generally are mottled brown on the dorsal side with a faintly yellow venter (underside) (Zweifel 1955, p. 231; Stebbins 2003, p. 460). Total tadpole length reaches 72 mm (2.8 in), the body is flattened, and the tail musculature is wide (about 2.5 cm (1 in) or more) before tapering into a rounded tip (Wright and Wright 1949, p. 431). The mouth has a maximum of eight labial (lip) tooth rows (two to four upper and four lower) (Stebbins 2003, p. 460). Tadpoles may take more than 1 year (Wright and Wright 1949, p. 431), and often require 2 to 4 years, to reach metamorphosis (transformation from tadpoles to frogs) (Cory 1962b, p. 515; Bradford 1983, pp. 1171, 1182; Bradford et al. 1993, p. 883; Knapp and Matthews 2000, p. 435), depending on local climate conditions and site-specific variables.
The time required to reach reproductive maturity in mountain yellow-legged frogs is thought to vary between 3 and 4 years post metamorphosis (Zweifel 1955, p. 254). This information, in combination with the extended amount of time as a tadpole before metamorphosis, means that it may take 5 to 8 years for mountain yellow-legged frogs to begin reproducing. While the typical lifespan of mountain yellow-legged frogs is largely unknown, Matthews and Miaud (2007, p. 991) estimated that the total lifespan (including tadpole and adult life stages) ranges up to 14 years, with other documented estimates of up to 16 years of age for the
Habitat and Life History
Mountain yellow-legged frogs currently exist in montane regions of the
At lower elevations within their historical range, these species have been associated with rocky streambeds and wet meadows surrounded by coniferous forest (Zweifel 1955, p. 237; Zeiner et al. 1988, p. 88), although, in general, little is known about the ecology of mountain yellow-legged frogs in
At higher elevations, these species occupy lakes, ponds, tarns (small steep-banked mountain lakes or pools, generally of glacial origin), and streams (Zweifel 1955, p. 237; Mullally and Cunningham 1956a, p. 191). Mountain yellow-legged frogs in the
Adult mountain yellow-legged frogs breed in a variety of habitats including the shallows of stillwater habitat (lakes or ponds) and flowing inlet streams (Zweifel 1955, p. 243; Pope 1999, p. 30). Adults emerge from overwintering sites immediately following snowmelt, and will even move over ice to reach breeding sites (Pope 1999, pp. 46-47; Vredenburg et al. 2005, p. 565). Mountain yellow-legged frogs deposit their eggs underwater in clusters, which they attach to rocks, gravel, or vegetation, or which they deposit under banks (Wright and Wright 1949, p. 431; Stebbins 1951, p. 341; Zweifel 1955, p. 243; Pope 1999, p. 30).
Lake depth is an important attribute defining habitat suitability for mountain yellow-legged frogs. At high elevations, both frogs and tadpoles overwinter under ice in lakes and streams. As tadpoles must overwinter multiple years before metamorphosis, successful breeding sites are located in (or connected to) lakes and ponds that do not dry out in the summer, and also are deep enough that they do not completely freeze or become oxygen-depleted (anoxic) in winter. Both adults and tadpole mountain yellow-legged frogs overwinter for up to 9 months in the bottoms of lakes that are at least 1.7 m (5.6 ft) deep; however, overwinter survival may be greater in lakes that are at least 2.5 m (8.2 ft) deep (Bradford 1983, p. 1179; Vredenburg et al. 2005, p. 565).
Bradford (1983, pp. 1173, 1178-1179) found that, in years with exceptional precipitation (61 percent above average) and greater than normal ice-depths, mountain yellow-legged frog die-offs sometimes result from oxygen depletion during winter in lakes less than 4 m (13 ft) in depth, finding that in ice-covered lakes, oxygen depletion occurs most rapidly in shallow lakes relative to deeper lakes. However, tadpoles may survive for months in nearly anoxic conditions when shallow lakes are frozen to the bottom. More recent work reported populations of mountain yellow-legged frogs overwintering in lakes less than 1.5 m (5 ft) deep that were assumed to have frozen to the bottom, and yet healthy frogs emerged the following July (Matthews and Pope 1999, pp. 622-623; Pope 1999, pp. 42-43). Matthews and Pope 1999, p. 619) used radio telemetry to find that, when lakes had begun to freeze over, the frogs were utilizing rock crevices, holes, and ledges near shore, where water depths ranged from 0.2 m (0.7 ft) to 1.5 m (5 ft). Vredenburg et al. (2005, p. 565) noted that such behavior may be a response to presence of introduced fish. Matthews and Pope (1999, p. 622) suggested that the granite surrounding these overwintering habitats probably insulates mountain yellow-legged frogs from extreme winter temperatures, and that they can survive, provided there is an adequate supply of oxygen.
Mountain yellow-legged frog tadpoles maintain a relatively high body temperature by selecting warmer microhabitats (Bradford 1984, p. 973). During winter, tadpoles remain in warmer water below the thermocline (the transition layer between thermally stratified water). After spring overturn (thaw and thermal mixing of the water), they behaviorally modulate their body temperature by moving to shallow, near-shore water when warmer days raise surface water temperatures. During the late afternoon and evening, mountain yellow-legged frogs retreat to offshore waters that are less subject to night cooling (Bradford 1984, p. 974).
Available evidence suggests that adult mountain yellow-legged frogs display strong site fidelity and return to the same overwintering and summer habitats from year to year (Pope 1999, p. 45; Matthews and Preisler 2010, p. 252). Matthews and Pope (1999, pp. 618-623) observed that the frogs' movement patterns and habitat associations shifted seasonally. Frogs were well-distributed in most lakes, ponds, and creeks during August, but moved to only a few lakes by October. Matthews and Pope (1999, pp. 618-623) established home-range areas for 10 frogs and found that frogs remained through August in the lake or creek where they'd been captured, with movement confined to areas ranging from 19.4 to 1,028 square meters (m2) (23.20 to 1,229 square yards (y2)). In September, movements increased, with home-ranges varying from 53 to 9,807 m2 in size (63.4 to 11,729 y2); six of nine frogs tagged in September moved from that lake by the end of the month, suggesting a pattern in which adult mountain yellow-legged frogs move among overwintering, breeding, and feeding sites during the year, with narrow distributions in early spring and late fall due to restricted overwintering habitat (Pope and Matthews 2001, p. 791). Although terrestrial movements of more than two or three hops from water were previously undocumented, overland movements exceeding 66 m (217 ft) were observed in 17 percent of tagged frogs, demonstrating that mountain yellow-legged frogs move overland as well as along aquatic pathways (Pope and Matthews 2001, p. 791). Pope and Matthews (2001, p. 791) also recorded a movement distance of over 1 km (including a minimum of 420 m (0.26 miles) overland movement and movement through a stream course). The farthest reported distance of a mountain yellow-legged frog from water is 400 m (1,300 ft) (Vredenburg 2002, p. 4).
Within stream systems,
Almost no data exist on the dispersal of juvenile mountain yellow-legged frogs away from breeding sites; however, juveniles that may be dispersing have been observed in small intermittent streams (Bradford 1991, p. 176). Regionally, mountain yellow-legged frogs are thought to exhibit a metapopulation structure (Bradford et al. 1993, p. 886; Drost and Fellers 1996, p. 424). Metapopulations are spatially separated population subunits within migratory distance of one another such that individuals may interbreed among subunits and populations may become reestablished if they are extirpated (Hanski and Simberloff 1997, p. 6).
Mountain yellow-legged frogs were historically abundant and ubiquitous across many of the higher elevations within the
Historically, the range of the
Historically, the northern DPS of the mountain yellow-legged frog ranged from the Monarch Divide in
Since the time of the mountain yellow-legged frog observations of Grinnell and Storer (1924, pp. 664-665), a number of researchers have reported disappearances of these species from a large fraction of their historical ranges in the
The current distributions of the
The most pronounced declines within the mountain yellow-legged frog complex have occurred north of
Population Estimates and Status
Monitoring efforts and research studies have documented substantial declines of mountain yellow-legged frog populations in the
Davidson et al. (2002, p. 1591) reviewed 255 previously documented mountain yellow-legged frog locations (based on Jennings and Hayes 1994, pp. 74-78) throughout the historical range and concluded that 83 percent of these sites no longer support frog populations. Vredenburg et al. (2007, pp. 369-371) compared recent survey records (1995-2004) with museum records from 1899-1994 and reported that 92.5 percent of historical
CDFW (CDFG (CDFW) 2011, pp. 17-20) used historical localities from museum records covering the same time interval (1899-1994), but updated recent locality information with additional survey data (1995-2010) to significantly increase proportional coverage from the Vredenburg et al. (2007) study. These more recent surveys failed to detect any extant frog populations (within 1 km (0.63 mi), a metric used to capture interbreeding individuals within metapopulations) at 220 of 318 historical
In addition to comparisons based on individual localities, CDFW (CDFG 2011, pp. 20-25) compared historical and recent population status at the watershed scale. This is a rough index of the geographic extent of the species through their respective ranges. Within the
Rangewide, declines of mountain yellow-legged frog populations were estimated at around one-half of historical populations by the end of the 1980s (Bradford et al. 1994, p. 323). Between 1988 and 1991, Bradford et al. (1994a, pp. 323-327) resurveyed sites known historically (1955 through 1979 surveys) to support mountain yellow-legged frogs. They did not detect frogs at 27 historical sites on the
Available information discussed below indicates that the rates of population decline have not abated, and they have likely accelerated during the 1990s into the 2000s. Drost and Fellers (1996, p. 417) repeated Grinnell and Storer's early 20th century surveys in
The USFS has been conducting a rangewide, long-term monitoring program for the
To summarize population trends over the available historical record, estimates range from losses between 69 to 93 percent of
Distinct Vertebrate Population Segment Analysis
Under the Act, we must consider for listing any species, subspecies, or, for vertebrates, any DPS of these taxa if there is sufficient information to indicate that such action may be warranted. To implement the measures prescribed by the Act, we, along with the
Under our DPS policy, three elements are considered in a decision regarding the status of a possible DPS as endangered or threatened under the Act. The elements are: (1) Discreteness of the population segment in relation to the remainder of the species to which it belongs; (2) the significance of the population segment to the species to which it belongs; and (3) the population segment's conservation status in relation to the Act's standards for listing. In other words, if we determine that a population segment of a vertebrate species being considered for listing is both discrete and significant, we would conclude that it represents a DPS, and thus a "species" under section 3(16) of the Act, whereupon we would evaluate the level of threat to the DPS based on the five listing factors established under section 4(a)(1) of the Act to determine whether listing the DPS as an "endangered species" or a "threatened species" is warranted.
Please refer to the proposed listing rule for detailed information about the distinct vertebrate population segment analysis for the northern DPS of the mountain yellow-legged frog (78 FR 24472,
Discreteness
Under our DPS Policy, a population segment of a vertebrate species may be considered discrete if it satisfies either of the following two conditions: (1) It is markedly separated from other populations of the same taxon as a consequence of physical, physiological, ecological, or behavioral factors (quantitative measures of genetic or morphological discontinuity may provide evidence of this separation); or (2) it is delimited by international governmental boundaries within which significant differences in control of exploitation, management of habitat, conservation, status, or regulatory mechanisms exist.
The analysis of the northern population segment of the mountain yellow-legged frog (Rana muscosa) (in the
Significance
Under our DPS Policy, once we have determined that a population segment is discrete, we consider its biological and ecological significance to the larger taxon to which it belongs. Our DPS policy provides several potential considerations that may demonstrate the significance of a population segment to the remainder of its taxon, including: (1) Evidence of the persistence of the discrete population segment in an ecological setting unusual or unique for the taxon, (2) evidence that loss of the discrete population segment would result in a significant gap in the range of the taxon, (3) evidence that the population segment represents the only surviving natural occurrence of a taxon that may be more abundant elsewhere as an introduced population outside its historic range, or (4) evidence that the discrete population segment differs markedly from the remainder of the species in its genetic characteristics.
We have found substantial evidence that three of the four significance criteria are met by the discrete northern population segment of the mountain yellow-legged frog that occurs in the
Evidence indicates that loss of the northern population segment of the mountain yellow-legged frog (in the
One of the most striking differences between the northern population segment and the southern population segment of the mountain yellow-legged frogs is the difference in the ecological setting in which they each persist. Zweifel (1955, pp. 237-241) observed that the frogs in southern
Finally, the northern population segment of the mountain yellow-legged frog is biologically significant based on genetic differences. Vredenburg et al. (2007, p. 361) identified that two of three distinct genetic clades (groups of distinct lineage) constitute the northern range of the mountain yellow-legged frog found in the
The loss of the northern population of the mountain yellow-legged frog would result in a significant gap in the range of the mountain yellow-legged frog species. The differences between the ecological settings for the southern population of mountain yellow-legged frogs (steep-gradient streams that seldom freeze) and the northern population of mountain yellow-legged frogs (high-elevation lakes and slow-moving portions of streams where frogs overwinter under ice and snow for up to 75 percent of the year) are significant. Additionally, the genetic distinction between these two populations reflects isolation for over a million years. Therefore based on the information discussed above, we find that northern population of the mountain yellow-legged frog (in the
DPS Conclusion
Based on the best scientific and commercial data available on distribution as well as ecological setting and genetic characteristics of the species, we have determined that the northern population segment of the mountain yellow-legged frog (in the
Summary of Changes From the Proposed Rule for the Sierra Nevada Yellow-Legged Frog and the Northern DPS of the Mountain Yellow-Legged Frog
Based on peer review, Federal and State, and public comments (see comments in the Summary of Comments and Recommendations section below), we have clarified information in the sections provided for the
In the proposed rule, we stated that grazing presented a minor prevalent threat. We reworded this final rule to more accurately reflect the contribution of legacy effects of past grazing levels to this threat assessment. We found that current livestock grazing that complies with forest standards and guidelines is not expected to negatively affect mountain yellow-legged frog populations in most cases, although limited exceptions could occur (where extant habitat is limited and legacy effects to meadows still require restoration, where habitat is limited such as in stream riparian zones or small meadows, or where grazing standards are exceeded). Rangewide, livestock grazing is not a substantial threat to the species.
In response to information provided during the public comment period, we added a discussion of mining activities in the Factor A discussion. In this final rule, we determine that, while most mining activities take place below the extant ranges of the species, where some types of mining activities occur, localized habitat-related effects may result.
We added new information available on packstock grazing, retaining our finding that packstock grazing is only likely to be a threat to mountain yellow-legged frogs in limited situations. We also added more information on roads and timber harvests, and we clarified that these activities primarily do not occur where there are extant populations (except where frogs occur in the northern or lower elevation portions of the range), and that USFS standards are generally designed to limit potential effects of such activities. We clarified the threat magnitude for roads and timber harvest from minor prevalence rangewide to not a threat to extant populations across much of the species' ranges (although they may pose important habitat-related effects to the species in localized areas). We reviewed information provided by the
We added a brief discussion of bullfrogs (Lithobates catesbeiana) under Factor C for mountain yellow-legged frogs noting that bullfrog predation and competition is expected to have population-level effects to mountain yellow-legged frog populations in those low elevation areas, or in the
We removed the discussion of contaminants under Factor E and refer readers to the proposed rule. Although we received additional information that clarified some text and provided additional references regarding contaminants, the clarifications supported our conclusions in the proposed rule that the best available information indicates that contaminants do not pose a current or continuing threat to the species. We also added additional information either available in our files, or provided by commenters, to clarify and support our finding on the threat of climate change. We revised the explanation in the determinations for each species to reflect the above changes.
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533), and its implementing regulations at 50 CFR part 424, set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, we may list a species based on any of the following five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination. Each of these factors is discussed below, and changes from the proposed rule (78 FR 24472,
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
A number of hypotheses, including habitat modification (including loss of vegetation, loss of wetlands, habitat modification for urban development, and degradation of upland habitats) have been proposed for recent global amphibian declines (Bradford et al. 1993, p. 883; Corn 1994, p. 62; Alford and Richards 1999, p. 134). However, physical habitat modification has not been associated with the rangewide decline of mountain yellow-legged frogs. Mountain yellow-legged frogs occur primarily at high elevations in the
However, other human activities may have played a role in the modification of mountain yellow-legged frog habitat. We have identified the following habitat-related activities as potentially relevant to the conservation status of the mountain yellow-legged frog complex: Fish introductions (see also Factor C, below), dams and water diversions, livestock grazing, timber management, road construction and maintenance, packstock use, recreational activities, and fire management activities. Such activities may have degraded habitat in ways that have reduced its capacity to sustain viable populations and may have fragmented and isolated mountain yellow-legged frog populations from each other.
One habitat feature that is documented to have a significant detrimental impact to mountain yellow-legged frog populations is the presence of introduced trout resulting from stocking programs for the creation and maintenance of a recreational fishery. To further angling success and opportunity, trout stocking programs in the
Prior to extensive trout planting programs, almost all streams and lakes in the
Some of the first practitioners of trout stocking in the
Brook trout (Salvelinus fontinalis), brown trout (Salmo trutta), rainbow trout (Oncorhynchus mykiss), and other trout species assemblages have been planted in most streams and lakes of the
Fish stocking as a practice has been widespread throughout the range of both species of mountain yellow-legged frogs. Knapp and Matthews (2000, p. 428) indicated that 65 percent of the water bodies that were 1 ha (2.5 ac) or larger in National Forests they studied were stocked with fish on a regular basis. Over 90 percent of the total water body surface area in the John Muir Wilderness was occupied by nonnative trout (Knapp and Matthews 2000, p. 434).
Another detrimental feature of fish stocking is that, in the
Thus, the frog's habitat has been modified due to the introduction of a nonnative predator that both competes for limited food resources and directly preys on mountain yellow-legged frog tadpoles and adults (see Factor C below). Presence of nonnative trout in naturally fishless ecosystems has had profound effects on the structure and composition of faunal assemblages, severely reducing not only amphibians, but also zooplankton and large invertebrate species (see Knapp 1996, p. 6; Bradford et al. 1998, p. 2489;
The body of scientific research has demonstrated that introduced trout have negatively impacted mountain yellow-legged frogs over much of the
Knapp and Matthews (2000, p. 428) surveyed more than 1,700 water bodies, and concluded that a strong negative correlation exists between introduced trout and mountain yellow-legged frogs (Knapp and Matthews 2000, p. 435). Consistent with this finding are the results of an analysis of the distribution of mountain yellow-legged frog tadpoles, which indicate that the presence and abundance of this life stage are reduced dramatically in fish-stocked lakes (Knapp et al. 2001, p. 408). Knapp (2005a, pp. 265-279) also compared the distribution of nonnative trout with the distributions of several amphibian and reptile species in 2,239 lakes and ponds in
Several aspects of the mountain yellow-legged frog's life history are thought to exacerbate its vulnerability to extirpation by trout (Bradford 1989, pp. 777-778; Bradford et al. 1993, pp. 886-888; Knapp 1996, p. 14; Knapp and Matthews 2000, p. 435). Mountain yellow-legged frogs are highly aquatic and are found primarily in lakes, most of which now contain trout (Knapp 1996, p. 14). In comparison to other Sierran frogs, mountain yellow-legged frog tadpoles generally need at least 2 years to reach metamorphosis, which restricts breeding to waters that are deep enough to avoid depletion of oxygen when ice-covered (Knapp 1996, p.14). Overwintering adults must also avoid oxygen depletion when the water is covered by ice, generally limiting overwintering to deeper waters that do not become anoxic (Mullally and Cunningham 1956a, p. 194; Bradford 1983, p. 1179; Knapp and Matthews 2000, pp. 435-436). At high elevations, both tadpoles and adults overwinter under ice for up to 9 months (Bradford 1983, p. 1171). These habitat requirements appear to restrict successful breeding and overwintering to the deeper water bodies where the chances of summer drying and winter freezing are reduced, the same water bodies that are most suitable for fishes; fishes also need deeper water bodies where the chances of summer drying and winter freezing are reduced (Bradford 1983, pp. 1172-1179; Knapp 1996, p. 14; Knapp and Matthews 2000, pp. 429, 435-436). Past fish-stocking practices targeted the deeper lakes, so the percentage of water bodies containing fish has increased with water depth, resulting in elimination of mountain yellow-legged frogs from once suitable habitats in which they were historically most common, and thereby generally isolating populations to the shallower, marginal habitats that do not have fish (Bradford 1983, pp. 1172-1179; Bradford et al. 1993, pp. 884, 886- 887; Knapp and Matthews 2000, pp. 435-436).
Mountain yellow-legged frogs and trout (native and nonnative) do co-occur at some sites, but these co-occurrences are generally thought to represent mountain yellow-legged frog "sink" populations (areas with negative population growth rates in the absence of immigration) (Bradford et al. 1998, p. 2489; Knapp and Matthews 2000, p. 436). Mountain yellow-legged frogs have also been extirpated at some fishless bodies of water (Bradford 1991, p. 176; Drost and Fellers 1996, p. 422). A possible explanation is the isolation and fragmentation of remaining populations due to introduced fishes in the streams that once provided mountain yellow-legged frogs with dispersal and recolonization routes; these remote populations are now non-functional as metapopulations (Bradford 1991, p. 176; Bradford et al. 1993, p. 887). Based on a survey of 95 basins within
Fragmentation of mountain yellow-legged frog habitat renders populations more vulnerable to extirpation from random events (such as disease) (Wilcox 1980, pp. 114-115; Bradford et al. 1993, p. 887; Hanski and Simberloff 1997, p. 21; Knapp and Matthews 2000, p. 436). Isolated population locations may have higher extinction rates because trout prevent successful recolonization and dispersal to and from these sites (Bradford et al. 1993, p. 887; Blaustein et al. 1994a, p. 7; Knapp and Matthews 2000, p. 436). If the distance between sites is too great, amphibians may not readily recolonize unoccupied sites following local extinctions because of physiological constraints, the tendency to move only short distances, and high site fidelity. Finally, frogs that do attempt recolonization may emigrate into fish-occupied habitat and perish, rendering sites with such metapopulation dynamics less able to sustain frog populations.
In 2001, CDFW revised fish stocking practices and implemented an informal policy on fish stocking in the range of the
As part of the
Since the mid-1990s, various parties, including researchers, CDFW, NPS, and the USFS, have implemented a variety of projects to actively restore habitat for the mountain yellow-legged frog via the removal of nonnative trout (USFS 2011, pp. 128-130; NPS 2013, pp. 3-5).
Although fish stocking has been curtailed within many occupied basins, the impacts to frog populations persist due to the presence of self-sustaining fish populations in some of the best habitat that normally would have sustained mountain yellow-legged frogs. The fragmentation that persists across the range of these frog species renders them more vulnerable to other population stressors, and recovery is slow, if not impossible, without costly and physically difficult direct human intervention (such as physical and chemical trout removal) (see Knapp et al. 2007a, pp. 11-19). While most of the impacts occurred historically, the impact upon the biogeographic (population/metapopulation) integrity of the species will be long-lasting. Currently, habitat degradation and fragmentation by fish is considered a highly significant and prevalent threat to persistence and recovery of the species.
Dams and Water Diversions
While a majority of dams and water diversions within the
Kondolf et al. (1996, p. 1014) report that dams can have direct effects to riparian habitat through permanent removal of habitat to construct roads, penstocks, powerhouses, canals, and dams. Impacts of reservoirs include flooding of riparian vegetation and impediments to establishment of new shoreline vegetation by fluctuating water levels. Dams can alter the temperature and sediment load of the rivers they impound (Cole and Landres 1996, p. 175). Dams, water diversions, and their associated structures can also alter the natural flow regime with unseasonal and fluctuating releases of water (Kondolf et al. 1996, p. 1014). We expect most such effects to occur in stream systems below the extant range of the mountain yellow-legged frogs, although it is possible that stream localities at the northern extent of the range or at low elevations may be affected (see also CDFW 2013, pp. 2-4).
The extent of past impacts to mountain yellow-legged frog populations from habitat loss or modification due to reservoir projects has not been quantified. CDFW (2013, p. 3) has noted that there are locations where the habitat inundated as the result of dam construction (for example,
Most of the dams constructed within the historic range of the mountain yellow-legged frogs are small streamflow-maintenance dams (CDFW 2013, p. 13) at the outflows of high-elevation lakes. These small dams may create additional habitat for the species and can act as barriers to fish migration from downstream tributaries into fishless habitats, although they do not impede frog movement (CDFW 2013, p. 3). CDFW staff (2013, p. 13) have observed that extant frog populations may have persisted where such dams have helped to preserve a fishless environment behind the dam.
Based on comments from CDFW and others and the provision of additional information, we have reviewed the analysis of dams and diversions that we presented in the proposed rule. We find that most large facilities are below the current range of the mountain yellow-legged frogs and have revised our finding. In the proposed rule, we stated that dams and diversions presented a moderate, prevalent threat to persistence and recovery of the species. In this final rule, we find that dams and water diversions present a minor, localized threat to persistence and recovery of the species where structures occur.
Livestock Use (Grazing)
The combined effect of legacy conditions from historically excessive grazing use and current livestock grazing activities has the potential to impact habitat in the range of the mountain yellow-legged frog. The following subsections discuss the effects of excessive historical grazing, current extent of grazing, and current grazing management practices. As discussed below, grazing has the potential to reduce the suitability of habitat for mountain yellow-legged frogs by reducing its capability to sustain frogs and facilitate dispersal and migration, especially in stream areas.
Grazing of livestock in riparian areas impacts the function of the aquatic system in multiple ways, including soil compaction, which increases runoff and decreases water availability to plants; vegetation removal, which promotes increased soil temperatures and evaporation rates at the soil surface; and direct physical damage to the vegetation (Kauffman and
Aquatic habitat can also be degraded by grazing. Mass erosion from trampling and hoof slide causes streambank collapse and an accelerated rate of soil transport to streams (Meehan and Platts 1978, p. 274). Accelerated rates of erosion lead to elevated instream sediment loads and depositions, and changes in stream-channel morphology (Meehan and Platts 1978, pp. 275-276; Kauffman and
Observational data indicate that livestock can negatively impact mountain yellow-legged frogs by altering riparian habitat (Knapp 1993a, p. 1; 1993b, p. 1; 1994, p. 3; Jennings 1996, p. 938; Carlson 2002, pers. comm.; Knapp 2002a, p. 29). Livestock tend to concentrate along streams and wet areas where there is water and herbaceous vegetation; grazing impacts are, therefore, most pronounced in these habitats (Meehan and Platts 1978, p. 274; U.S. Government Accounting Office (GAO) 1988, pp. 10-11; Fleischner 1994, p. 635; Menke et al. 1996, p. 17). This concentration of livestock contributes to the destabilization of streambanks, causing undercuts and bank failures (Kauffman et al. 1983, p. 684; Marlow and Pogacnik 1985, pp. 282-283; Knapp and Matthews 1996, p. 816; Moyle 2002, p. 55). Grazing activity can contribute to the downcutting of streambeds and lower the water table. The degree of erosion caused by livestock grazing can vary with slope gradient, aspect, soil condition, vegetation density, and accessibility to livestock, with soil disturbance greater in areas overused by livestock (Meehan and Platts 1978, pp. 275-276; Kauffman et al. 1983, p. 685; Kauffman and
Livestock grazing may impact other wetland systems, including ponds that can serve as mountain yellow-legged frog habitat. Grazing can modify shoreline habitats by removing overhanging banks that provide shelter, and grazing contributes to the siltation of breeding ponds. Bradford (1983, p. 1179) and Pope (1999, pp. 43-44) have documented the importance of deep lakes to overwinter survival of these species. We expect that pond siltation due to grazing may reduce the depth of breeding ponds and cover underwater crevices in some circumstances where grazing is heavy and where soils are highly erodable, thereby making the ponds less suitable, or unsuitable, as overwintering habitat for tadpoles and adult mountain yellow-legged frogs.
Effects of Excessive Historical Grazing
In general, historical livestock grazing within the range of the mountain yellow-legged frog was at a high (although undocumented), unregulated and unsustainable level until the establishment of National Parks (beginning in 1890) and National Forests (beginning in 1905) (UC 1996a, p. 114; Menke et al. 1996, p. 14). Historical evidence indicates that heavy livestock use in the
Effects of Current Grazing
Yosemite,
USFS standards and guidelines in forest land and resource management plans have been implemented to protect water quality, sensitive species, vegetation, and stream morphology. Further, USFS standards have been implemented in remaining allotments to protect aquatic habitats (see discussion of the aquatic management strategy under Factor D for examples). USFS data from long-term meadow monitoring collected from 1999 to 2006 indicate that most meadows appear to be in an intermediate quality condition class, with seeming limited change in condition class over the first 6 years of monitoring. In addition, USFS grazing standards and guidelines are based on current science and are designed to improve or maintain range ecological conditions, and standards for managing habitat for threatened, endangered, and sensitive species have also been incorporated (Brown et al. 2009, pp. 56-58). The seasonal turn-out dates (dates at which livestock are permitted to move onto USFS allotments) are set yearly based on factors such as elevation, annual precipitation, soil moisture, and forage plant phenology, and meadow readiness dates are also set for montane meadows. However, animals turned out to graze on low-elevation range (until higher elevation meadows are ready) may reach upper portions of allotments before the meadows have reached range readiness (Brown et al. 2009, p. 58).
Menke et al. (1996) have reported that grazing livestock in numbers that are consistent with grazing capacity and use of sustainable methods led to better range management in the
In summary, the legacy effects to habitat from historical grazing levels, such as increased erosion, stream downcutting and headcutting, lowered water tables, and increased siltation, are a threat to mountain yellow-legged frogs in those areas where such conditions still occur and may need active restoration. In the proposed rule, we stated that grazing presented a minor prevalent threat. Based on USFS and public comments, we have reevaluated our analysis of grazing to clarify effects of past versus current grazing. We have reworded the finding to more accurately reflect the contribution of legacy effects of past grazing levels to this threat assessment, as follows: Current livestock grazing activities may present an ongoing, localized threat to individual populations in locations where the populations occur in stream riparian zones and in small waters within meadow systems, where active grazing co-occurs with extant frog populations. Livestock grazing that complies with forest standards and guidelines is not expected to negatively affect mountain yellow-legged frog populations in most cases, although limited exceptions could occur, especially where extant habitat is limited. In addition, mountain yellow-legged frogs may be negatively affected where grazing standards are exceeded. Rangewide, current livestock grazing is not a substantial threat to the species.
Mining
Several types of mining activities have occurred, or may currently occur, on National Forests, including aggregate mining (the extraction of materials from streams or stream terraces for use in construction), hardrock mining (the extraction of minerals by drilling or digging into solid rock), hydraulic mining (a historical practice using pressurized water to erode hillsides, outlawed in 1884), placer mining (mining in sand or gravel, or on the surface, without resorting to mechanically assisted means or explosives), and suction-dredge mining (the extraction of gold from riverine materials, in which water, sediment, and rocks are vacuumed from portions of streams and rivers, sorted to obtain gold, and the spoils redeposited in the stream (see review in Brown et al. 2009, pp. 62-64).
Aggregate mining can alter sediment transport in streams, altering and incising stream channels, and can cause downstream deposition of sediment, altering or eliminating habitat. Aggregate mining typically occurs in large riverine channels that are downstream of much of the range of the mountain yellow-legged frog complex (see review in Brown et al. 2009, pp. 62-64). However, Brown et al. (2009, pp. 62-64) note that effects of aggregate mining may occur in some portions of the
Hardrock mining can be a source of pollution where potentially toxic metals are solubilized by waters that are slightly acidic. Past mining activities have resulted in the existence of many shaft or tunnel mines on the forest in the
Hydraulic mining has exposed previously concealed rocks that can increase pollutants such as acid, cadmium, mercury, and asbestos, and its effect on water pollution may still be apparent on the
Brown et al. (2009, p. 64) report that suction-dredge mining is also primarily recreational noting that, because nozzles are currently restricted to 6 inches or smaller, CDFW (CDFG, 1994) expects disturbed areas to recover quickly (although CDFW notes that such dredging may increase suspended sediments, change stream geomorphology, and bury or suffocate larvae). Suction dredge mining occurs primarily in the foothills of the
The high-elevation areas where most
Packstock Use
Similar to cattle, horses and mules may significantly overgraze, trample, or pollute riparian and aquatic habitat if too many are concentrated in riparian areas too often or for too long. Commercial packstock trips are permitted in National Forests and National Parks within the
Packstock use is likely a threat of low significance to mountain yellow-legged frogs at the current time, except on a limited, site-specific basis. As
Roads and Timber Harvest
Activities that alter the terrestrial environment (such as road construction and timber harvest) may impact amphibian populations in the
Timber harvest activities (including vegetation management and fuels management) remove vegetation and cause ground disturbance and compaction, making the ground more susceptible to erosion (Helms and Tappeiner 1996, p. 446). This erosion can increase siltation downstream and potentially damage mountain yellow-legged frog breeding habitat. Timber harvest may alter the annual hydrograph (timing and volume of surface flows) in areas where harvests occur. The majority of erosion caused by timber harvests is from logging roads (Helms and Tappeiner 1996, p. 447). A recent monitoring effort, which was conducted by the USFS in stream habitats in the northern part of the
Roadways have the potential to affect riparian habitat by altering the physical and chemical environment, including alteration of surface-water run-off, with potential changes to hydrology in high-mountain lake and stream systems (Brown et al. 2009, pp. 71-72). Roads, including those associated with timber harvests, have also been found to contribute to habitat fragmentation and limit amphibian movement, thus having a negative effect on amphibian species richness. Therefore, road construction could fragment mountain yellow-legged frog habitat if a road bisects habitat consisting of water bodies in close proximity. In the prairies and forests of
Currently, most of the mountain yellow-legged frog populations occur in National Parks or designated wilderness areas where timber is not harvested (Bradford et al. 1994, p. 323; Drost and Fellers 1996, p. 421; Knapp and Matthews 2000, p. 430) and where motorized access (and roads) does not occur. Mountain yellow-legged frog populations outside of these areas are most often located above the timberline, so timber harvest activity is not expected to affect the majority of extant mountain yellow-legged frog populations. There is a higher potential overlap of timber harvest activities with the species in the northern and lower elevation portions of the species' ranges where the frogs occur in streams and meadows in forested environments; in these areas, populations are very small and fragmented (Brown 2013, unpaginated). Likewise, at lower elevations of the
In riparian areas, the USFS generally maintains standards and guidelines for land management activities, such as timber harvests, that are designed to maintain the hydrologic, geomorphic, and ecologic processes that directly affect streams, stream processes, and aquatic habitats, and which can limit potential effects of such activities (Foote et al. 2013, pp. 4, 32). In general, we expect the standards to be effective in preventing habitat-related effects to these species. Additionally, neither timber harvests nor roads have been implicated as important contributors to the decline of this species (Jennings 1996, pp. 921-941), although habitat alterations due to these activities may, in site-specific, localized cases, have population-level effects to mountain yellow-legged frogs. We expect that such cases would be more likely at lower elevations or in the more northern portion of the species' range where limited extant populations occur in close proximity to timber harvest, or where populations occur in drainages adjacent to roadways. In the proposed rule, we stated that roads and timber harvest likely present minor prevalent threats to the mountain yellow-legged frogs factored across the range of the species. We are clarifying that language, noting that they may pose important habitat-related effects to the species in localized areas, but are not likely threats across most of the species' ranges.
Fire and Fire Management Activities
Mountain yellow-legged frogs are generally found at high elevations in wilderness areas and National Parks where vegetation is sparse and where fire may have historically played a limited role in the ecosystem. However, at lower elevations and in the northern portion of the range, mountain yellow-legged frogs occur in stream or lake environments within areas that are forested to various extents. In some areas within the current range of the mountain yellow-legged frog, long-term fire suppression has changed the forest structure and created conditions that increase fire severity and intensity (McKelvey et al. 1996, pp. 1934-1935). Excessive erosion and siltation of mountain yellow-legged frog habitats following wildfire is a concern where shallow, lower elevation aquatic areas occur below forested stands. However, prescribed fire has been used by land managers to achieve various silvicultural objectives, including fuel load reduction. In some systems, fire is thought to be important in maintaining open aquatic and riparian habitats for amphibians (Russell et al. 1999, p. 378), although severe and intense wildfires may reduce amphibian survival, as the moist and permeable skin of amphibians increases their susceptibility to heat and desiccation (Russell et al. 1999, p. 374). Amphibians may avoid direct mortality from fire by retreating to wet habitats or sheltering in subterranean burrows.
The effects of past fire and fire management activities on historical populations of mountain yellow-legged frogs are not known. Neither the direct nor indirect effects of prescribed fire or wildfire on the mountain yellow-legged frog have been studied. Hossack et al. (2012, pp. 221, 226), in a study of the effects of six stand-replacing fires on three amphibians that breed in temporary ponds in low-elevation dense coniferous forests or in high-elevation open, subalpine forests in
Recreation
Recreational activities that include hiking, camping, and backpacking take place throughout the
In easily accessible areas, heavy foot traffic in riparian areas can trample vegetation, compact soils, and physically damage stream banks (Kondolf et al. 1996, pp. 1014, 1019). Human foot, horse, bicycle, or off-highway motor vehicle trails can replace riparian habitat with compacted soil (Kondolph et al. 1996, pp. 1014, 1017, 1019), lower the water table, and cause increased erosion where such activities occur. Bahls (1992, p. 190) reported that the recreational activity of anglers at high mountain lakes can be locally intense in western wilderness areas, with most regions reporting a level of use greater than the fragile lakeshore environments can withstand. Heavy recreation use has been associated with changes in the basic ecology of lakes. In the 1970s,
Because of demand for wilderness recreational experiences and concern about wilderness resource conditions, wilderness land management now includes standards for wilderness conditions, implementing permit systems and group-size limits for visitors and packstock, prohibitions on camping and packstock use close to water, and other visitor management techniques to reduce impacts to habitat, including riparian habitat (Cole 2001, pp. 4-5). These wilderness land management techniques are currently being used in National Forest Wilderness areas in the
In summary, based on the best available scientific and commercial information, we consider the modification of habitat and curtailment of the species' ranges to be a significant and ongoing threat to the
Factor B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
No commercial market for mountain yellow-legged frogs exists, nor any documented recreational or educational uses for these species. Scientific research may cause stress to mountain yellow-legged frogs through disturbance, including disruption of the species' behavior, handling of individual frogs, and injuries associated with marking and tracking individuals. However, this is a relatively minor nuisance and not likely a negative impact to the survival and reproduction of individuals or the viability of the populations.
Based on the best available scientific and commercial information, we do not consider overutilization for commercial, recreational, scientific, or educational purposes to be a threat to the mountain yellow-legged frog complex now or in the future.
Factor C. Disease or Predation
Predation
Researchers have observed predation of mountain yellow-legged frogs by the mountain garter snake (Thamnophis elegans elegans), Brewer's blackbird (Euphagus cyanocephalus), Clark's nutcracker (Nucifraga columbiana), coyote (Canis latrans), and black bear (Ursus americanus) (Mullally and Cunningham 1956a, p. 193; Bradford 1991, pp. 176-177; Jennings et al. 1992, p. 505; Feldman and Wilkinson 2000, p. 102; Vredenburg et al. 2005, p. 565). However, none of these has been implicated as a driver of population dynamics, and we expect that such predation events do not generally have population-level impacts except where so few individuals remain that such predation is associated with loss of a population (Bradford 1991, pp 174-177; Jennings 1996, p. 938).
The American bullfrog (Lithobates catesbeiana) is native to
The most prominent predator of mountain yellow-legged frogs is introduced trout, whose significance is well-established because it has been repeatedly observed that the frogs rarely coexist with fish, and it is known that introduced trout can and do prey on all frog life stages except for eggs (Grinnell and Storer 1924, p. 664; Mullally and Cunningham 1956a, p. 190; Cory 1962a, p. 401; 1963, p. 172; Bradford 1989, pp. 775-778; Bradford and Gordon 1992, p. 65; Bradford et al. 1993, pp. 882-888; 1994a, p. 326; Drost and Fellers 1996, p. 422; Jennings 1996, p. 940; Knapp 1996, p. 14; Knapp and Matthews 2000, p. 428; Knapp et al. 2001, p. 401; Vredenburg 2004, p. 7649; Knapp 2013, unpaginated). Knapp (1996, pp. 1-44) estimated that 63 percent of lakes larger than 1 ha (2.5 ac) in the
The multiple-year tadpole stage of the mountain yellow-legged frog requires submersion in the aquatic habitat year-round until metamorphosis. Moreover, all life stages are highly aquatic, increasing the frog's susceptibility to predation by trout (where they co-occur) throughout its lifespan. Overwinter mortality due to predation is especially significant because, when water bodies ice over in winter, adults and tadpoles move from shallow margins of lakes and ponds into deeper unfrozen water where they are more vulnerable to predation; fish encounters in such areas increase, while refuge is less available.
The predation of mountain yellow-legged frogs by fishes observed in the early 20th century by Grinnell and Storer and the documented population declines of the 1970s (Bradford 1991, pp. 174-177; Bradford et al. 1994, pp. 323-327; Stebbins and Cohen 1995, pp. 226-227) were not the beginning of the mountain yellow-legged frog's decline, but rather the continuation of a long decline that started soon after fish introductions to the
Disease
Over roughly the last 2 decades, pathogens have been associated with amphibian population declines, mass die-offs, and even extinctions worldwide (Bradford 1991, pp. 174-177; Blaustein et al. 1994b, pp. 251-254; Alford and Richards 1999, pp. 506; Muths et al. 2003, p. 357; Weldon et al. 2004, p. 2100; Rachowicz et al. 2005, p. 1446; Fisher et al. 2009, p. 292). One pathogen strongly associated with dramatic declines on all continents that harbor amphibians (all continents except
Bd affects the mouth parts and epidermal (skin) tissue of tadpoles and metamorphosed frogs (Fellers et al. 2001, pp. 950-951). The fungus can reproduce asexually, and can generally withstand adverse conditions such as freezing or drought (Briggs et al. 2002, p. 38). It also may reproduce sexually, leading to thick-walled sporangia that would be capable of long-term survival (for distant transport and persistence in sites even after all susceptible host animal populations are extirpated) (Morgan et al. 2007, p. 13849). Adult frogs can acquire this fungus from tadpoles, and it can also be transmitted between tadpoles (Rachowicz and Vredenburg 2004, p. 80).
In California, chytridiomycosis has been detected in many amphibian species, including mountain yellow-legged frogs (Briggs et al. 2002, p. 38; Knapp 2002b, p. 1). The earliest documented case in the mountain yellow-legged frog complex was in 1998, at
During the epidemic phase of chytrid infection into unexposed populations, rapid die-offs of adult and subadult lifestages are observed (Vredenburg et al. 2010, p. 9691), with metamorphs being extremely sensitive to Bd infection (Kilpatrick et al. 2009, p. 113; Vredenburg et al. 2010, p. 9691; see also Vredenburg 2013, unpaginated). Field and laboratory experiments indicate that Bd infection is generally lethal to mountain yellow-legged frogs (Knapp 2005b; Rachowicz 2005, pers. comm.), and is likely responsible for declines in sites that were occupied as recently as 2002, but where frogs were absent by 2005 (Knapp 2005b). Rachowicz et al. (2006, p. 1671) monitored several infected and uninfected populations in
In several areas where detailed studies of the effects of Bd on the mountain yellow-legged frog are ongoing, substantial declines have been observed following the course of the disease infection and spread. Survey results from 2000 in
The effects of Bd on host populations of the mountain yellow-legged frog are variable, ranging from extirpation to persistence with a low level of infection (Briggs et al. 2002, pp. 40-41). When Bd infection first occurs in a population, the most common outcome is epidemic spread of the disease and population extirpation (Briggs et al. 2010, p. 9699). Die-offs are characterized by rapid onset of high-level Bd infections, followed by death due to chytridiomycosis. Although most populations that are newly exposed to Bd are driven to extirpation following the arrival of Bd, some populations that experience Bd-caused population crashes are not extirpated, and some may even recover despite ongoing chytridiomycosis (Briggs et al. 2010, pp. 9695-9696). However, it is apparent that even at sites exhibiting population persistence with Bd, high mortality of metamorphosing frogs persists, and this phenomenon may explain the lower abundances observed in such populations (Briggs et al. 2010, p. 9699).
Vredenburg et al. (2010a, pp. 2-4) studied frog populations before, during, and after the infection and spread of Bd in three study basins constituting 13, 33, and 42 frog populations, respectively, then comprising the most intact metapopulations remaining for these species throughout their range. The spread of Bd averaged 688 m/year (yr) (2,257 ft/yr), reaching all areas of the smaller basin in 1 year, and taking 3 to 5 years to completely infect the larger basins, progressing like a wave across the landscape. The researchers documented die-offs following the spread of Bd, with decreased population growth rates evident within the first year of infection. Basinwide, metapopulations crashed from 1,680 to 22 individuals (northern DPS of the mountain yellow-legged frog) in
Vredenburg et al. (2010a, p. 3) projected that, at current extinction rates, and given the disease dynamics of Bd (infected tadpoles succumb to chytridiomycosis at metamorphosis), most if not all, extant populations within the recently infected basins they studied would go extinct within the next 3 years. Available data (CDFW, unpubl. data; Knapp 2005b; Rachowicz 2005, pers. comm.; Rachowicz et al. 2006, p. 1671) indicate that Bd is now widespread throughout the
Other diseases have also been reported as adversely affecting amphibian species, and these may be present within the range of the mountain yellow-legged frog. Bradford (1991, pp. 174-177) reported an outbreak of red-leg disease in
Saprolegnia is a globally distributed fungus that commonly attacks all life stages of fishes (especially hatchery-reared fishes), and has recently been documented to attack and kill egg masses of western toads (Bufo boreas) (Blaustein et al. 1994b, p. 252). This pathogen may be introduced through fish stocking, or it may already be established in the aquatic ecosystem. Fishes and migrating or dispersing amphibians may be vectors for this fungus (Blaustein et al. 1994b, p. 253; Kiesecker et al. 2001, p. 1068). Saprolegnia has been reported in the southern DPS of the mountain yellow-legged frog (North 2012, pers. comm.); however, its occurrence within the Sierran range of the mountain yellow-legged frog complex and associated influence on population dynamics (if any) are unknown.
Other pathogens of concern for amphibian species include ranaviruses (Family Iridoviridae). Mao et al. (1999, pp. 49-50) isolated identical iridoviruses from co-occurring populations of the threespine stickleback (Gasterosteus aculeatus) and the red-legged frog (Rana aurora), indicating that infection by a given virus is not limited to a single species, and that iridoviruses can infect animals of different taxonomic classes. This suggests that virus-hosting trout introduced into mountain yellow-legged frog habitat may be a vector for amphibian viruses. However, definitive mechanisms for the transmission to the mountain yellow-legged frog remain unknown. No viruses were detected in the mountain yellow-legged frogs that Fellers et al. (2001, p. 950) analyzed for Bd. In
It is unknown whether amphibian pathogens in the high
The contribution of Bd as an environmental stressor and limiting factor on mountain yellow-legged frog population dynamics is currently extremely high, and it poses a significant current and continuing threat to remnant uninfected populations in the southern
In summary, based on the best available scientific and commercial information, we consider the threats of predation and disease to be significant, ongoing threats to the
Factor D. The Inadequacy of Existing Regulatory Mechanisms
In determining whether the inadequacy of regulatory mechanisms constitutes a threat to the mountain yellow-legged frog complex, we analyzed the existing Federal and State laws and regulations that may address the threats to these species or contain relevant protective measures. Regulatory mechanisms are typically nondiscretionary and enforceable, and may preclude the need for listing if such mechanisms are judged to adequately address the threat(s) to the species such that listing is not warranted. Conversely, threats on the landscape are not ameliorated where existing regulatory mechanisms are not adequate (or when existing mechanisms are not adequately implemented or enforced).
Federal Wilderness Act
The Wilderness Act of 1964 (16 U.S.C.
National Forest Management Act of 1976
Under the National Forest Management Act of 1976, as amended (NFMA) (16 U.S.C.
On
Sierra Nevada Forest Plan Amendment
In 2001, a record of decision was signed by the USFS for the Sierra Nevada Forest Plan Amendment (SNFPA), based on the final environmental impact statement for the SNFPA effort and prepared under the 1982 NFMA planning regulations.
Relevant to the mountain yellow-legged frog complex, the Record of Decision for SNFPA aims to protect and restore aquatic, riparian, and meadow ecosystems, and to provide for the viability of associated native species through implementation of an aquatic management strategy. The aquatic management strategy is a general framework with broad policy direction. Implementation of this strategy was intended to take place at the landscape and project levels. Nine goals are associated with the aquatic management strategy:
(1) The maintenance and restoration of water quality to comply with the Clean Water Act (CWA) and the Safe Drinking Water Act;
(2) The maintenance and restoration of habitat to support viable populations of native and desired nonnative riparian-dependent species, and to reduce negative impacts of nonnative species on native populations;
(3) The maintenance and restoration of species diversity in riparian areas, wetlands, and meadows to provide desired habitats and ecological functions;
(4) The maintenance and restoration of the distribution and function of biotic communities and biological diversity in special aquatic habitats (such as springs, seeps, vernal pools, fens, bogs, and marshes);
(5) The maintenance and restoration of spatial and temporal connectivity for aquatic and riparian species within and between watersheds to provide physically, chemically, and biologically unobstructed movement for their survival, migration, and reproduction;
(6) The maintenance and restoration of hydrologic connectivity between floodplains, channels, and water tables to distribute flood flows and to sustain diverse habitats;
(7) The maintenance and restoration of watershed conditions as measured by favorable infiltration characteristics of soils and diverse vegetation cover to absorb and filter precipitation, and to sustain favorable conditions of streamflows;
(8) The maintenance and restoration of instream flows sufficient to sustain desired conditions of riparian, aquatic, wetland, and meadow habitats, and to keep sediment regimes within the natural range of variability; and
(9) The maintenance and restoration of the physical structure and condition of streambanks and shorelines to minimize erosion and sustain desired habitat diversity.
If these goals of the aquatic management strategy are pursued and met, threats to the mountain yellow-legged frog complex resulting from habitat alterations could be reduced. However, the aquatic management strategy is a generalized approach that does not contain specific implementation timeframes or objectives, and it does not provide direct protections for the mountain yellow-legged frog. Additionally, as described above, the
National Park Service Organic Act
The statute establishing the
Federal Power Act
The Federal Power Act of 1920, as amended (FPA) (16 U.S.C. 791 et seq.) was enacted to regulate non-federal hydroelectric projects to support the development of rivers for energy generation and other beneficial uses. The FPA provides for cooperation between the
Although most reservoirs and water diversions are located at lower elevations than those at which extant mountain yellow-legged frog populations occur, numerous extant populations occur within watersheds that feed into developed and managed aquatic systems (such as reservoirs and water diversions) operated for the purpose of power generation and regulated by the FPA and may be considered during project relicensing.
State
California Endangered Species Act
This section has been updated from the information presented in the proposed rule, and discussion of CDFW's current fish-stocking practices has been moved to the Factor A discussion of
The California Endangered Species Act (CESA) (California Fish and Game Code, section 2080 et seq.) prohibits the unauthorized take of State-listed endangered or threatened species. CESA requires State agencies to consult with CDFW on activities that may affect a State-listed species, and mitigate for any adverse impacts to the species or its habitat. Pursuant to CESA, it is unlawful to import or export, take, possess, purchase, or sell any species or part or product of any species listed as endangered or threatened. The State may authorize permits for scientific, educational, or management purposes, and allow take that is incidental to otherwise lawful activities. On
While the listing of the
Overall, existing Federal and State laws and regulatory mechanisms currently offer some level of protection for the mountain yellow-legged frog complex. While not the intent of the Wilderness Act, the mountain yellow-legged frogs receive ancillary protection from the Wilderness Act due to its prohibitions on development, road construction, and timber harvest, and associated standards and guidelines that limit visitor and packstock group sizes and use. With the exception of the National Park Service Organic Act, the existing regulatory mechanisms have not been effective in reducing threats to mountain yellow-legged frogs and their habitat from fish stocking and the continuing presence of nonnative fish. Nor have these mechanisms been effective in protecting populations from infection by diseases, although
Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence
The mountain yellow-legged frog is sensitive to environmental change or degradation because it has an aquatic and terrestrial life history and highly permeable skin that increases exposure of individuals to substances in the water, air, and terrestrial substrates (Blaustein and Wake 1990, p. 203; Bradford and Gordon 1992. p. 9; Blaustein and Wake 1995, p. 52; Stebbins and Cohen 1995, pp. 227-228). Several natural or anthropogenically influenced changes, including contaminant deposition, acid precipitation, increases in ambient ultraviolet radiation, and climate change, have been implicated as contributing to amphibian declines (Corn 1994, pp. 62-63; Alford and Richards 1999, pp. 2-7). There are also documented incidences of direct mortality of, or the potential for direct disturbance to, individuals from some activities already discussed; in severe instances, these actions may have population-level consequences. As presented in the proposed rule (78 FR 24472,
Climate Change
Our analysis under the Act includes consideration of ongoing and projected changes in climate. The terms "climate" and "climate change" are defined by the
Global climate projections are informative and, in some cases, the only or the best scientific information available for us to use. However, projected changes in climate and related impacts can vary substantially across and within different regions of the world (for example, IPCC 2007a, pp. 8-12). Therefore, we use downscaled projections when they are available and have been developed through appropriate scientific procedures, because such projections provide higher resolution information that is more relevant to the spatial scales used for analyses of a given species (see
Variability exists in outputs from different climate models, and uncertainty regarding future GHG emissions is also a factor in modeling (PRBO 2011, p. 3). A general pattern that holds for many predictive models indicates northern areas of
The last century has included some of the most variable climate reversals documented, at both the annual and near-decadal scales, including a high frequency of
For the
Snow-dominated elevations of 2,000-2,800 m (6,560-9,190 ft) will be the most sensitive to temperature increases, and a warming of 5 [degrees] C (9 [degrees] F) is projected to shift center timing (the measure when half a stream's annual flow has passed a given point in time) to more than 45 days earlier in the year as compared to the 1961-1990 baseline (PRBO 2011, p. 23). Lakes, ponds, and other standing waters fed by snowmelt or streams are likely to dry out or be more ephemeral during the non-winter months (Lacan et al. 2008, pp. 216-222; PRBO 2011, p. 24). This pattern could influence ground water transport, and springs may be similarly depleted, leading to lower lake levels.
Blaustein et al. (2010, pp. 285-300) provide an exhaustive review of potential direct and indirect and habitat-related effects of climate change to amphibian species, with documentation of effects in a number of species where such effects have been studied. Altitudinal range shifts with changes in climate have been reported in some regions. They note that temperature can influence the concentration of dissolved oxygen in aquatic habitats, with warmer water generally having lower concentrations of dissolved oxygen, and that water balance heavily influences amphibian physiology and behavior. They predict that projected changes in temperature and precipitation are likely to increase habitat loss and alteration for those species living in sensitive habitats, such as ephemeral ponds and alpine habitats (Blaustein et al. 2010, pp. 285-287).
Because environmental cues such as temperature and precipitation are clearly linked to onset of reproduction in many species, climate change will likely affect the timing of reproduction in many species, potentially with different sexes responding differently to climate change. For example, males of two newt species (Triturus spp.) showed a greater degree of change in arrival date at breeding ponds (Blaustein et al. 2010, p. 288). Lower concentrations of dissolved oxygen in aquatic habitats may negatively affect developing embryos and larvae, in part because increases in temperature increase the oxygen consumption rate in amphibians. Reduced oxygen concentrations have also been shown to result in accelerated hatching in ranid frogs, but at a smaller size, while larval development and behavior may also be affected and may be mediated by larval density and food availability (Blaustein et al. 2010, pp. 288-289).
Increased temperatures can reduce time to metamorphosis, which can increase chances of survival where ponds dry, but also result in metamorphosis at a smaller size, suggesting a likely trade-off between development and growth, which may be exacerbated by climate change and have fitness consequences for adults (Blaustein et al. 2010, pp. 289-290). Changes in terrestrial habitat, such as changed soil moisture and vegetation, can also directly affect adult and juvenile amphibians, especially those adapted to moist forest floors and cool, highly oxygenated water that characterizes montane regions. Climate change may also interact with other stressors that may be acting on a particular species, such as disease and contaminants (Blaustein et al. 2010, pp. 290-299).
A recent paper (Kadir et al. 2013, entire) provides specific information on the effects of climate change in the
Vulnerability of species to climate change is a function of three factors: Sensitivity of a species or its habitat to climate change, exposure of individuals to such physical changes in the environment, and their capacity to adapt to those changes (
Exposure to environmental stressors renders species vulnerable to climate change impacts, either through direct mechanisms (for example, physical temperature extremes or changes in solar radiation), or indirectly through impacts upon habitat (hydrology; fire regime; or abundance and distribution of prey, competitors, or predator species). A species' capacity to adapt to climate change is increased by behavioral plasticity (the ability to modify behavior to mitigate the impacts of the stressor), dispersal ability (the ability to relocate to meet shifting conditions), and evolutionary potential (for example, shorter lived species with multiple generations have more capacity to adapt through evolution) (
The International Union for Conservation of Nature describes five categories of life-history traits that render species more vulnerable to climate change (Foden et al. 2008 in
At high elevations, where most extant populations occur, mountain yellow-legged frogs depend on high mountain lakes where both adult and larval frogs overwinter under ice for up to 9 months of the year. Overwintering under ice poses physiological problems for the frogs, most notably the depletion of oxygen in the water during the winter (Bradford 1983, p. 1171). Bradford (1983, pp. 1174-1182) has found, based on lab and field results, that tadpoles are more resistant to low dissolved oxygen levels than adult frogs; after two drought years that were followed by a severe winter, all frogs in 21 of 26 study lakes were lost (with the exception of one 2.1-m (6.9-ft) deep lake that contained only one individual), while tadpoles survived in all but one of the shallowest lakes. Losses were apparently due to oxygen depletion in a year when there was exceptional precipitation, ice depths that were thicker than usual, and lake thawing was 5 to 6 weeks later than the previous year. The survival of adults in substantial numbers was significantly correlated with lake depth and confined to lakes deeper than 4 m (13.1 ft).
Bradford (1983, pp. 1174-1179) found that mean oxygen concentration in lakes was directly related to maximum lake depth, with dissolved oxygen levels declining throughout the winter. He also found that a thickened ice layer on a lake causes the lake to become effectively more shallow, leading to an increased rate of oxygen depletion (Bradford 1983, p. 1178). Studies of winterkill of fish due to oxygen depletion also show that oxygen depletion is inversely related to lake depth and occurs most rapidly in shallow lakes relative to deeper lakes (See review in
In summer, reduced snowpack and enhanced evapotranspiration following higher temperatures can dry out ponds that otherwise would have sustained rearing tadpoles (Lacan et al. 2008, p. 220), and may also reduce fecundity (egg production) (Lacan et al. 2008, p. 222). Lacan et al. (2008, p. 211) observed that most frog breeding occurred in the smaller, fishless lakes of
Earlier snowmelt is expected to cue breeding earlier in the year. The advance of this primary signal for breeding phenology in montane and boreal habitats (Corn 2005, p. 61) may have both positive and negative effects. Additional time for growth and development may render larger individuals more fit to overwinter; however, earlier breeding may also expose young tadpoles (or eggs) to killing frosts in more variable conditions of early spring (Corn 2005, p. 60).
Whether mountain yellow-legged frogs depend on other species that may be affected either positively or negatively by climate change is unclear. Climate change may alter invertebrate communities (PRBO 2011 p. 24). In one study, an experimental increase in stream temperature was shown to decrease density and biomass of invertebrates (Hogg and Williams 1996, p. 401). Thus, climate change might have a negative impact on the mountain yellow-legged frog prey base.
Indirect effects from climate change may lead to greater risk to mountain yellow-legged frog population persistence. For example, fire intensity and magnitude are projected to increase (PRBO 2011, pp. 24-25), and, therefore, the contribution and influence of this stressor upon frog habitat and populations will increase. Climate change may alter lake productivity through changes in water chemistry, the extent and timing of mixing, and nutrient inputs from increased fires, all of which may influence community dynamics and composition (Melack et al. 1997, p. 971; Parker et al. 2008, p. 12927). These changes may not all be negative; for example, water chemistry and nutrient inputs, along with warmer summer temperatures, could increase net primary productivity in high mountain lakes to enhance frog food sources, although changes in net primary productivity may also negatively affect invertebrate prey species endemic to oligotrophic lakes (low nutrient, low productivity).
Carey (1993, p. 359) has suggested that, where environmental changes cause sufficient stress to cause immunological suppression, cold body temperatures that montane amphibians experience over winter could play a synergistic role in reducing further immunological responses to disease. Thus, such conditions might make mountain yellow-legged frogs more susceptible to disease. Additionally, Blaustein et al. (2001, p. 1808) have suggested that climate change could also affect the distribution of pathogens and their vectors, exposing amphibians to new pathogens. Climate change (warming) has been hypothesized as a driver for the range shift of Bd (Pounds et al. 2006, p. 161; Bosch et al. 2007, p. 253). However, other work has indicated that survival and transmission of Bd is more likely facilitated by cooler and wetter conditions (Corn 2005, p. 63). Fisher et al. (2009, p. 299) present a review of information available to date and evaluate the competing hypotheses regarding Bd dynamics, and they present some cases that suggest a changing climate can change the host-pathogen dynamic to a more virulent state.
The key risk factor for climate change impacts on mountain yellow-legged frogs is likely the combined effect of reduced water levels in high mountain lakes and ponds and the relative inability of individuals to disperse and colonize across longer distances in order to occupy more favorable habitat conditions (if they exist). Although such adaptive range shifts have been observed in some plant and animal species, they have not been reported in amphibians. The changes observed in amphibians to date have been more associated with changes in timing of breeding (phenology) (Corn 2005, p. 60). This limited adaptive capacity for mountain yellow-legged frogs is a function of high site fidelity and the extensive habitat fragmentation due to the introduction of fishes in many of the more productive and persistent high mountain lake habitats and streams that constitute critical dispersal corridors throughout much of the frogs' range (see Factor C discussion above).
An increase in the frequency, intensity, and duration of droughts caused by climate change may have compounding effects on populations of mountain yellow-legged frogs already in decline. In situations where other stressors (such as introduced fish) have resulted in the isolation of mountain yellow-legged frogs in marginal habitats, localized mountain yellow-legged frog population crashes or extirpations resulting from drought may exacerbate their isolation and preclude natural recolonization (Bradford et al. 1993, p. 887; Drost and Fellers 1996, p. 424; Lacan et al. 2008, p. 222). Viers et al. (2013, pp. 55, 56) have used a variety of risk metrics to determine that both mountain yellow-legged frog species in the
Direct and Indirect Mortality
Other risk factors include direct and indirect mortality as an unintentional consequence of activities within mountain yellow-legged frog habitat. Mortality due to trampling by grazing livestock has been noted in a limited number of situations, with expected mortality risk thought to be greatest if livestock concentrate in prime breeding habitat early in the season when adults are breeding and egg masses are present (Brown et al. 2009, p. 59). Brown et al. (2009, p. 59) note that standards in the SNFPA are intended to mitigate this risk. Recreational uses also have the potential to result in direct or indirect mortality of mountain yellow-legged frog individuals at all life stages.
Small Population Size
In many localities, remaining populations for both the
Compared to large populations, small populations are more vulnerable to extirpation from environmental, demographic, and genetic stochasticity (random natural occurrences), and unforeseen (natural or unnatural) catastrophes (
Environmental stochasticity refers to annual variation in birth and death rates in response to weather, disease, competition, predation, or other factors external to the population (
Allee effects (Dennis 1989, pp. 481-538) occur when a population loses its positive stock-recruitment relationship (when population is in decline). In a declining population, an extinction threshold or "
The extinction risk for a species represented by few small populations is magnified when those populations are isolated from one another. This is especially true for species whose populations normally function in a metapopulation structure, whereby dispersal or migration of individuals to new or formerly occupied areas is necessary. Connectivity between these populations is essential to increase the number of reproductively active individuals in a population; mitigate the genetic, demographic, and environmental effects of small population size; and recolonize extirpated areas. Additionally, fewer populations by itself increases the risk of extinction.
The combination of low numbers with the other extant stressors of disease, fish persistence, and potential for climate extremes could have adverse consequences for the mountain yellow-legged frog complex as populations approach the
Cumulative Impacts of Extant Threats
Stressors may act additively or synergistically. An additive effect would mean that an accumulation of otherwise low threat factors acting in combination may collectively result in individual losses that are meaningful at the population level. A synergistic effect is one where the interaction of one or more stressors together leads to effects greater than the sum of those individual factors combined. Further, the cumulative effect of multiple added stressors can erode population viability over successive generations and act as a chronic strain on the viability of a species, resulting in a progressive loss of populations over time. Such interactive effects from compounded stressors thereby act synergistically to curtail the viability of frog metapopulations and increase the risks of extinction.
It is difficult to predict the precise impact of the cumulative threat represented by the relatively novel Bd epidemic across a landscape already fragmented by fish stocking. The singular threat of the Bd epidemic wave in the uninfected populations of the mountain yellow-legged frog complex in the southern
In summary, based on the best available scientific and commercial information, we consider other natural and manmade factors to be substantial ongoing threats to the
Determination for the Sierra Nevada Yellow-Legged Frog
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the
Threats that face the
Historical livestock grazing activities may also have modified the habitat of the
Competitive exclusion and predation by fish have eliminated or reduced mountain yellow-legged frog populations in stocked habitats, and left remnant populations isolated, while bullfrogs are expected to have negative effects where they occur (Factor C). It is important to recognize that, throughout the vast majority of its range,
Sierra Nevada yellow-legged frogs are vulnerable to multiple pathogens (see Factor C) whose effects range from low levels of infection within persistent populations to disease-induced extirpation of entire populations. The Bd epidemic has caused extirpations of
These threats described above are likely to be exacerbated by widespread changes associated with climate change and by current small population sizes in many locations (see Factor E), while instances of direct and indirect mortality are expected to have population-level effects only in relatively uncommon, localized situations. On a rangewide basis, the existing regulatory mechanisms (Factor D) have not been effective in protecting populations from declines due to fish stocking and continuing presence of fish and to disease, although standards and guidelines developed by the USFS and the NPS have largely limited threats due to livestock and packstock grazing, recreation, and timber use.
The main and interactive effects of these various risk factors have acted to reduce
Given the life history of this species, dispersal, recolonization, and genetic exchange are largely precluded by the fragmentation of habitat common throughout its current range as a result of fish introductions. Frogs that may disperse are susceptible to hostile conditions in many circumstances. In essence,
The Act defines an endangered species as any species that is "in danger of extinction throughout all or a significant portion of its range" and a threatened species as any species "that is likely to become endangered throughout all or a significant portion of its range within the foreseeable future." We find that the
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the species, and have determined that the
Under the Act and our implementing regulations, a species may warrant listing if it is endangered or threatened throughout all or a significant portion of its range. The
Final Determination for the Northern DPS of the Mountain Yellow-Legged Frog
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the northern DPS of the mountain yellow-legged frog. The best available information for the northern DPS of the mountain yellow-legged frog shows that the geographic extent of the species' range has declined, with local population-level changes first noticed in the early 1900s (Grinnell and Storer 1924, p. 664), although they were still abundant at many sites in the
Threats that face the northern DPS of the mountain yellow-legged frog, discussed above under Factors A, C, D, and E, increase the risk of the species' extinction, given the isolation of remaining populations. The best available science indicates that the introduction of fishes to the frog's habitat to support recreational angling is one of the primary causes of the decline of the northern DPS of the mountain yellow-legged frog and poses a current and continuing threat to the species (Factor A). Water bodies throughout this range have been intensively stocked with introduced fish (principally trout). It is a threat of significant influence, and although fewer lakes are stocked currently than were stocked prior to 2001, it remains prevalent today because fish persist in many high-elevation habitats even where stocking has ceased. Recolonization in these situations is difficult for a highly aquatic species with high site fidelity and unfavorable dispersal conditions. Climate change is likely to exacerbate these other threats and further threaten population resilience.
Historical livestock grazing activities may also have modified the habitat of the northern DPS of the mountain yellow-legged frog throughout much of its range (Factor A). Grazing pressure has been significantly reduced from historical levels, but is expected to have legacy effects to mountain yellow-legged frog habitat where prior downcutting and headcutting of streams have resulted in reduced water tables that still need restoration to correct. Current grazing that complies with forest standards and guidelines is not expected to cause habitat-related effects to the species in almost all cases, but in limited cases may continue to contribute to some localized degradation and loss of suitable habitat. The habitat-related effects of recreation, packstock grazing, dams and water diversions, roads, timber harvests, and fire management activities on the northern DPS of the mountain yellow-legged frog (Factor A) may have contributed to historical losses when protections and use limits that are currently afforded by USFS and NPS standards and guidelines did not exist. Currently, Federal agencies with jurisdiction within the current range of the northern DPS of the mountain yellow-legged frog have developed management standards and guidelines that limit habitat damage due to these activities, although in localized areas habitat-related changes may continue to affect individual populations.
Competitive exclusion and predation by fish have eliminated or reduced mountain yellow-legged frog populations in stocked habitats, and left remnant populations isolated, while bullfrogs are expected to have negative effects where they occur (Factor C). It is important to recognize that throughout the vast majority of its range, the northern DPS of the mountain yellow-legged frogs did not co-evolve with any species of fish, as this species predominantly occurs in water bodies above natural fish barriers. Consequently, the species has not evolved defenses against fish predation.
Mountain yellow-legged frogs are vulnerable to multiple pathogens (see Factor C) whose effects range from low levels of infection within persistent populations to disease-induced extirpation of entire populations. The Bd epidemic has caused rangewide extirpations of populations of the northern DPS of the mountain yellow-legged frog and associated significant declines in numbers of individuals. Though Bd was only recently discovered to affect the mountain yellow-legged frog, it appears to infect populations at much higher rates than other pathogens. The imminence of this risk to currently uninfected habitats is immediate, and the potential effects severe. The already-realized effects to the survival of sensitive amphibian life stages in Bd-positive areas are well-documented. Although some populations survive the initial Bd wave, survival rates of metamorphs and population viability are markedly reduced relative to historical (pre-Bd) norms.
These threats are likely to be exacerbated by widespread changes associated with climate change and by current small population sizes in many locations (see Factor E), while instances of direct and indirect mortality are expected to have population-level effects only in relatively uncommon, localized situations. Rangewide, the existing regulatory mechanisms (Factor D) have not been effective in protecting populations from declines due to fish stocking and continuing presence of fish and to disease, although standards and guidelines developed by the USFS and the NPS have largely limited threats due to livestock and packstock grazing, recreation, and timber use.
The main and interactive effects of these various risk factors have acted to reduce the northern DPS of the mountain yellow-legged frog to a small fraction of its historical range and reduce population abundances significantly throughout most of its current range. Populations of this species in remaining areas in the southern
Given the life history of this species, dispersal, recolonization, and genetic exchange are largely precluded by the fragmentation of habitat common throughout its current range as a result of fish introductions. Frogs that may disperse are susceptible to hostile conditions in many circumstances. In essence, mountain yellow-legged frogs have been marginalized by historical fish introductions. Populations have recently been decimated by Bd, and the accumulation of other stressors (such as anticipated reduction of required aquatic breeding habitats with climate change and more extreme weather) upon a fragmented landscape make adaptation and recovery a highly improbable scenario without active intervention. The cumulative risk from these stressors to the persistence of the mountain yellow-legged frog throughout its range is significant.
The Act defines an endangered species as any species that is "in danger of extinction throughout all or a significant portion of its range" and a threatened species as any species "that is likely to become endangered throughout all or a significant portion of its range within the foreseeable future." We find that the northern DPS of the mountain yellow-legged frog is presently in danger of extinction throughout its entire range, based on the immediacy, severity, and scope of the threats described above. Specifically, these include habitat degradation and fragmentation under Factor A, predation and disease under Factor C, and climate change and the interaction of these various stressors cumulatively impacting small remnant populations under Factor E. There has been a rangewide reduction in abundance and geographic extent of surviving populations of the northern DPS of the mountain yellow-legged frog following decades of fish stocking, habitat fragmentation, and, most recently, a disease epidemic. Surviving populations are smaller and more isolated, and recruitment in Bd-positive populations is much reduced relative to historical norms. This combination of population stressors makes species persistence precarious throughout the current range in the
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the species, and have determined that the northern DPS of the mountain yellow-legged frog, meets the definition of endangered under the Act, rather than threatened. This is because significant threats are occurring now and will occur in the future, at a high magnitude and across the DPS' entire range, making the northern DPS of the mountain yellow-legged frog in danger of extinction at the present time. The rate of population decline remains high in the wake of Bd epidemics, and northern DPS of the mountain yellow-legged frog areas are at high, imminent risk. The recent rates of decline for these populations are even higher than declines in the populations of the
Under the Act and our implementing regulations, a species may warrant listing if it is endangered or threatened throughout all or a significant portion of its range. The northern DPS of the mountain yellow-legged frog addressed in this final listing rule is restricted in its range, and the threats occur throughout the remaining occupied habitat. Therefore, we assessed the status of this DPS throughout its entire range in the
Summary of Biological Status and Threats Affecting the Yosemite Toad
Background
Taxonomy and Species Description
Please refer to the proposed listing rule for the
Habitat and Life History
Breeding habitat--
Yosemite toads were found as often at large as at small sites (Liang 2010, p. 19), suggesting that this species is capable of successfully utilizing small habitat patches. Liang also found that population persistence was greater at higher elevations, with an affinity for relatively flat sites with a southwesterly aspect (Liang 2010, p. 20; see also Mullally 1953, p. 182). These areas receive higher solar radiation and are capable of sustaining hydric (wet), seasonally ponded, and mesic (moist) breeding and rearing habitat. The
Adults are thought to be long-lived, and this factor allows for persistence in variable conditions and more marginal habitats where only periodic good years allow high reproductive success (USFS et al. 2009, p. 27). Females have been documented to reach 15 years of age, and males as many as 12 years (Kagarise Sherman and Morton 1993, p. 195); however, the average longevity of the
Adults appear to have high site-fidelity; Liang (2010, pp. 99, 100) found that the majority of individuals identified in multiple years were located in the same meadow pools, although individuals will move between breeding areas (Liang 2010, p. 52; Liang 2013, p. 561). Breeding habitat includes shallow, warm-water areas in wet meadows, such as shallow ponds and flooded vegetation, ponds, lake edges, and slow-flowing streams (Karlstrom 1962, pp. 8-12; Brown 2013, unpaginated). Tadpoles have also been observed in shallow areas of lakes (Mullally 1953, pp. 182-183).
Adult Yosemite toads are most often observed near water, but only occasionally in water (Mullally and Cunningham 1956b, pp. 57-67). Moist upland areas such as seeps and springheads are important summer nonbreeding habitats for adult toads (Martin 2002, pp. 1-3). The majority of their life is spent in the upland habitats proximate to their breeding meadows. They use rodent burrows for overwintering and probably for temporary refuge during the summer (Jennings and Hayes 1994, pp. 50-53), and they spend most of their time in burrows (Liang 2010, p. 95). They also use spaces under surface objects, including logs and rocks, for temporary refuge (Stebbins 1951, pp. 245-248; Karlstrom 1962, pp. 9-10). Males and females also likely inhabit different areas and habitats when not breeding, and females tend to move farther from breeding ponds than males (USFS et al. 2009, p. 28).
Males exit burrows first, and spend more time in breeding pools than females, who do not breed every year (Kagarise Sherman and Morton, 1993, p. 196). Data suggest that higher lipid storage in females, which enhances overwinter survival, also precludes the energetic expense of breeding every year (Morton 1981, p. 237). The
Eggs hatch within 3-15 days, depending on ambient water temperatures (Kagarise Sherman 1980, pp. 46-47; Jennings and Hayes 1994, p. 52). Tadpoles typically metamorphose around 40-50 days after fertilization, and are not known to overwinter (Jennings and Hayes 1994. p. 52). Tadpoles are black in color, tend to congregate together (Brattstrom 1962, pp. 38-46) in warm shallow waters during the day (Cunningham 1963, pp. 60-61), and then retreat to deeper waters at night (Mullaly 1953, p. 182). Rearing through metamorphosis takes approximately 5-7 weeks after eggs are laid (USFS et al. 2009, p. 25). Toads need shallow, warm surface water that persists through the period during which they metamorphose; shorter hydroperiods in that habitat can reduce reproductive success (Brown 2013, unpaginated).
Reproductive success is dependent on the persistence of tadpole rearing sites and conditions for breeding, egg deposition, hatching, and rearing to metamorphosis (USFS et al. 2009, p. 23). Given their association with shallow, ephemeral habitats,
Yosemite toads can move farther than 1 km (0.63 mi) from their breeding meadows (average movement is 275 m (902 ft)), and they utilize terrestrial environments extensively (Liang 2010, p. 85). The average distance traveled by females is twice as far as males, and home ranges for females are 1.5 times greater than those for males (Liang 2010, p. 94). Movement into the upland terrestrial environment following breeding does not follow a predictable path, and toads tend to traverse longer distances at night, perhaps to minimize evaporative water loss (Liang 2010, p. 98). Martin (2008, p. 123) tracked adult toads during the active season and found that on average toads traveled a total linear distance of 494 m (1,620 ft) within the season, with minimum travel distance of 78 m (256 ft) and maximum of 1.76 km (1.09 mi).
The known historical range of the
The current range of the
BILLING CODE 4310-55-P
See Illustration in Original Document.
BILLING CODE 4310-55-C
Population Estimates and Status
Baseline data on the number and size of historical
One pair of studies allows us to compare current distribution with historic distributions and indicates that large reductions have occurred. In 1915 and 1919, Grinnell and Storer (1924, pp. 657-660) surveyed for vertebrates at 40 sites along a 143-km (89-mi) west-to-east transect across the
Another study comparing historic and current occurrences also found a large decline in
A third study comparing historic and recent surveys indicates declines in
The only long-term, site-specific population study for
Kagarise Sherman and Morton (1993, pp. 186-198) also conducted occasional surveys of six other populations in the eastern
The most reliable information about
Moreover, overall abundances in the intensively monitored watersheds were very low (fewer than 20 males per meadow per year) relative to other historically reported abundances of the species (Brown et al. 2011, p. 4). Brown et al. (2011, p. 35) suggest that populations are now very small across the range of the species. During their monitoring over the past decade, they found only 18 percent of occupied survey watersheds range-wide had "large" populations (more than 1,000 tadpoles or 100 of any other lifestage detected at the time of survey). While not all surveys were conducted at the peak of tadpole presence and adults are not reliably found outside of the breeding season, Brown et al. (2012) surveyed many sites at appropriate times and rarely found the large numbers of tadpoles or metamorphs that would be expected if population sizes were similar to those reported historically. The researchers interpret these data, in combination with documented local population declines from other studies (see above), to support the hypothesis that population declines have occurred range-wide (Brown et al. 2012, p. 11).
Summary of Changes From the Proposed Rule for the Yosemite Toad
Based on peer review and Federal, State, and public comments (see comments in the Summary of Comments and Recommendations section, below), we clarified information for the
In the Summary of Factors Affecting the Species section, under Factor A, we made small changes to the discussion about meadow loss and degradation in order to improve clarity. In the Livestock Use (Grazing) Effects to Meadow Habitat section, we reorganized the information and separated the effects of historic livestock grazing from the effects due to current grazing levels, and we added additional references received from the USFS. In the Roads and Timber Harvest Effects to Meadow Habitat section, we clarified the extent to which these activities overlap with the
In the Fire Management section, we added information to clarify that
In Factor B, we added information provided during the comment period, which documented the sale of one
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533), and its implementing regulations at 50 CFR part 424, set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, we may list a species based on any of the following five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination. Each of these factors is discussed below, and changes from the proposed rule (78 FR 24472,
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
The habitat comprising the current range of the
Meadow
Some of the habitat effects associated with grazing activities that were described for the mountain yellow-legged frogs (see the Summary of Factors Affecting the Species section for those species, above) also apply to
Given the reliance of the
Since the existence of meadows is largely dependent on their hydrologic setting, most meadow degradation is due fundamentally to hydrologic alterations (Stillwater Sciences 2008, p. 13). There are many drivers of hydrologic alterations in meadow ecosystems. In some locations, historic water development and ongoing water management activities have physically changed the underlying hydrologic system. Diversion and irrigation ditches formed a vast network that altered local and regional stream hydrology, although these manmade systems are generally below the range of the
Land uses causing channel erosion are a threat to
The hydrologic effects of stream incision on the groundwater system may significantly impact groundwater storage, affecting late summer soil moisture and facilitating vegetation change (Bergmann 2004, pp. 24-31). For example, in the northern
Mountain meadows in the western
Livestock Use (Grazing) Effects to Meadow Habitat
The combined effect of legacy conditions from historically excessive grazing use and current livestock grazing activities have the potential to impact habitat in the range of the
Overgrazing has been associated with accelerated erosion and gullying of meadows (Kattelmann and Embury 1996, pp. 13, 18), which leads to siltation and more rapid succession of meadows. Grazing can cause erosion by disturbing the ground, damaging and reducing vegetative cover, and destroying peat layers in meadows, which lowers the groundwater table and summer flows (Armour et al. 1994, pp. 9-12; Martin 2002, pp. 1-3; Kauffman and
Heavy grazing can alter vegetative species composition and contribute to lodgepole pine (Pinus contorta) invasion (Ratliff 1985, pp. 33-36). Lowering of the water table facilitates encroachment of conifers into meadows. Gully formation and lowering of water tables, changes in the composition of herbaceous vegetation, increases in the density of forested stands, and the expansion of trees into areas that formerly were treeless have been documented in
Effects of Historical Livestock Grazing
Grazing of livestock in
Grazing within the National Forests has continued into recent times, with reduction in activity (motivated by resource concerns, conflicts with other uses, and deteriorating range conditions) beginning in the 1920s. A brief wartime increase in the 1940s followed, before grazing continued to be scaled back beginning in the 1950s through the early 1970s. However, despite these reductions, grazing still exceeded sustainable capacity in many areas (Menke et al. 1996, p. 9; UC 1996a, p. 115). Historical evidence indicates that heavy livestock use in the
Livestock grazing in the
Due to the long history (Menke et al. 1996, Ch. 22, pp. 1-52) of livestock and packstock grazing in the
Effects of Current Livestock Grazing
Currently, approximately 33 percent of the estimated range of the
The influence of grazing on toad populations in recent history is uncertain, despite more available data on land use and
It is important to note that the results of these studies did not present a direct measurement of toad survival (for example, mark--recapture analysis of population trends), and the design was limited in numbers of years and treatment replicates. It is plausible that, for longer lived species with irregular female breeding activity over the time course of this particular study, statistical power was not sufficient to discern a treatment effect. Further, a time lag could occur between effect and discernible impacts, and significant confounding variability in known drivers such as interannual variation in climate.
Additionally, the experimental design in the studies tested the hypothesis that forest management guidelines (at 40 percent use threshold) were impacting toad populations, and this limited some analyses and experimental design to sites with lower treatment intensities. Researchers reported annual utilization by cattle ranging from 10-48 percent, while individual meadow use ranged from 0-76 percent (the SNFPA allowable use is capped at 40 percent) (Allen-Diaz et al. 2010, p. 5). As a result of the study design, the Allen-Diaz study does not provide sufficient information on the impacts of grazing on
The researchers observed significant variation in young-of-year occupancy in pools between meadows and years, and within meadows over years (Allen-Diaz et al. 2010, p. 7). This variability would likely mask treatment effects, unless the grazing variable was a dominant factor driving site occupancy, and the magnitude of the effect was quite severe. Further, in an addendum to the initial report, Lind et al. (2011b, pp. 12-14) report statistically significant negative (inverse) relationships for tadpole density and grazing intensity (tadpole densities decreased when percent use exceeded between 30 and 40 percent). This result supports the hypothesis that grazing at intensities approaching and above the 40 percent threshold can negatively affect
Allen-Diaz et al. (2010, p. 2) and Roche et al. (2012b, pp. 6-7) found that toad occupancy is strongly driven by meadow wetness (hydrology) and suggested attention should focus on contemporary factors directly impacting meadow wetness, such as climate, fire regime changes, and conifer encroachment (see Factor A above). The researchers also stated that meadow use by cattle during the grazing season is driven by selection of plant communities found in drier meadows (Allen-Diaz et al. 2010, p. 2). This suggests that the apparent differences in preference could provide for some segregation of toad and livestock use in meadow habitats, so that at least direct mortality threats may be mitigated by behavioral isolation. Based on the limitations of the study as described above, we find the initial results from Allen-Diaz et al. (2010, pp. 1-45) to be inconclusive to discern the impacts of grazing on
The available grazing studies focus on breeding habitat (wet meadows) and do not consider impacts to upland habitats. The USFS grazing guidelines for protection of meadow habitats of the
Although we lack definitive data to assess the link between
Roads and Timber Harvest Effects to Meadow Habitat
Road construction and use, along with timber harvest activity, may impact
Prior to the formation of National Parks and National Forests, timber harvest was widespread and unregulated in the
The majority of forest roads in National Forests of the
We expect that the majority of timber harvest, road development, and associated management impacts (see "Effects of Fire Suppression on Meadow Habitats" below) to
Effects of Fire Suppression on Meadow Habitats
Fire management refers to activities over the past century to combat forest fires. Historically, both lightning-caused fires and fires ignited by American Indians were regularly observed in western forests (Parsons and Botti 1996, p. 29), and in the latter 19th century, the active use of fire to eliminate tree canopy in favor of forage plants continued by sheepherders (Kilgore and Taylor 1979, p. 139). Beginning in the 20th century, land management in the
Long-term fire suppression has influenced forest structure and altered ecosystem dynamics in the
Evidence indicates that fire plays a significant role in the evolution and maintenance of lower elevation forested meadows of the
While no studies have confirmed a link between fire suppression and rangewide population decline of the
Recreation and Packstock Effects to Meadow Habitat
Recreational activities take place throughout the
Although much
Packstock use has similar effects to those discussed for livestock grazing (for additional information on current packstock use levels and management protections, see the Packstock Use section under the mountain yellow-legged frogs, above), although this risk factor is potentially more problematic as this land use typically takes place in more remote and higher-elevation areas occupied by
Habitat-related effects of recreational activities on the
Dams and Water Diversions Effects to Meadow Habitat
Past construction of dams, diversion, and irrigation ditches resulted in a vast man-made network that altered local and regional stream hydrology in the
Past construction of these reservoirs likely contributed to the decline of the
Climate Effects to Meadow Habitat
Different studies indicate that multiple drivers are behind the phenomenon of conifer encroachment into meadows. The first factor affecting the rate of conifer encroachment into meadow habitats, fire suppression, was discussed above. Climate variability is another factor affecting the rate of conifer encroachment on meadow habitats. A study by Franklin et al. (1971, p. 215) concluded that fire had little influence on meadow maintenance in their study area, while another study concluded that climate change is a more likely explanation for encroachment of trees into the adjacent meadow at their site, rather than fire suppression or changes in grazing intensity (Dyer and Moffett, 1999, p. 444).
Climatic variability is strongly correlated with tree encroachment into dry subalpine meadows (Jakubos and Romme 1993, p. 382). In the
Our analyses under the Act include consideration of ongoing and projected changes in climate. The terms "climate" and "climate change" are defined by the
For the
Snow-dominated elevations from 2,000-2,800 m (6,560-9,190 ft) will be the most sensitive to temperature increases (PRBO 2011, p. 23). Meadows fed by snowmelt may dry out or be more ephemeral during the non-winter months (PRBO 2011, p. 24). This pattern could influence groundwater transport, and springs may be similarly depleted, leading to lower water levels in available breeding habitat and decreased area and hydroperiod (i.e., duration of water retention) of suitable habitat for rearing tadpoles of
Blaustein et al. (2010, pp. 285-300) provide an exhaustive review of potential direct and indirect and habitat-related effects of climate change to amphibian species, with documentation of effects in a number of species where such effects have been studied. Altitudinal range shifts with changes in climate have been reported in some regions. They note that temperature can influence the concentration of dissolved oxygen in aquatic habitats, with warmer water generally having lower concentrations of dissolved oxygen, and that water balance heavily influences amphibian physiology and behavior. They predict that projected changes in temperature and precipitation are likely to increase habitat loss and alteration for those species living in sensitive habitats, such as ephemeral ponds and alpine habitats (Blaustein et al. 2010, pp. 285-287).
Because environmental cues such as temperature and precipitation are clearly linked to onset of reproduction in many species, climate change will likely affect the timing of reproduction in many species, potentially with different sexes responding differently to climate change. For example, males of two newt species (Triturus spp.) showed a greater degree of change in arrival date at breeding ponds (Blaustein et al. 2010, p. 288). Lower concentrations of dissolved oxygen in aquatic habitats may negatively affect developing embryos and larvae, in part because increases in temperature increase the oxygen consumption rate in amphibians. Reduced oxygen concentrations have also been shown to result in accelerated hatching in ranid frogs, but at a smaller size, while larval development and behavior may also be affected and may be mediated by larval density and food availability (Blaustein et al. 2010, pp. 288-289).
Increased temperatures can reduce time to metamorphosis, which can increase chances of survival where ponds dry, but also result in metamorphosis at a smaller size, suggesting a likely trade-off between development and growth, which may be exacerbated by climate change and have fitness consequences for adults (Blaustein et al. 2010, pp. 289-290). Changes in terrestrial habitat, such as changed soil moisture and vegetation, can also directly affect adult and juvenile amphibians, especially those adapted to moist forest floors and cool, highly oxygenated water that characterizes montane regions. Climate change may also interact with other stressors that may be acting on a particular species, such as disease and contaminants (Blaustein et al. 2010, pp. 290-299).
A recent paper (Kadir et al. 2013, entire) provides specific information on the effects of climate change in the
Historically, drought is thought to have contributed to the decline of the
Davidson et al. (2002, p. 1598) analyzed geographic decline patterns for the
Most recently, modeled vulnerability assessments for
The breeding ecology and life history of the
In summary, based on the best available scientific and commercial information, we consider the threats of destruction, modification, and curtailment of the species' habitat and range to be significant ongoing threats to the
Factor B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes
We do not have any scientific or commercial information to indicate that overutilization for commercial, recreational, or scientific purposes poses a threat to the
Scientific research may cause some stress to
Based on the best available scientific and commercial information, we do not consider overutilization for commercial, recreational, scientific, or educational purposes to be a threat to the
Factor C. Disease or Predation
Predation
Prior to the trout stocking of high
Drost and Fellers (1994, pp. 414-425) suggested that
The observed predation of
Overall, the data and available literature suggest that direct mortality from fish predation is likely not an important factor driving
Other predators may also have an effect on
Disease
Although not all vectors have been confirmed in the
Various diseases are confirmed to be lethal to
Die-offs in
Saprolegnia ferax, a species of water mold that commonly infects fish in hatcheries, caused a massive lethal infection of eggs of western toads at a site in
Sadinski (2004, p. 35) discovered that mortality of
Until recently, the contribution of Bd infection to
Carey (1993, pp. 355-361) developed a model to explain the disappearance of boreal toads (Bufo boreas boreas) in the
Although disease as a threat factor to the
In summary, based on the best available scientific and commercial information, we do not consider predation to be a threat to the species. We consider disease to be a threat to the
Factor D. The Inadequacy of Existing Regulatory Mechanisms
In determining whether the inadequacy of regulatory mechanisms constitutes a threat to the
We discussed the applicable State and Federal laws and regulations, including the Wilderness Act, NFMA above (see Factor D discussion for mountain yellow-legged frogs). In general, the same administrative policies and statutes are in effect for the
Taylor Grazing Act of 1934
In response to overgrazing of available rangelands by livestock from the 1800s to the 1930s,
Existing Federal and State laws and regulatory mechanisms currently offer some level of protection for the
Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence
The Yosemite toad is sensitive to environmental change or degradation due to its life history, biology, and existence in ephemeral habitats characterized by climate extremes and low productivity. It is also sensitive to anthropogenically influenced factors. For example, contaminants, acid precipitation, ambient ultraviolet radiation, and climate change have been implicated as contributing to amphibian declines (Corn 1994, pp. 62-63; Alford and Richards 1999, pp. 2-7). However, as with the case with the mountain yellow-legged frog complex, contaminants, acid precipitation, and ambient ultraviolet radiation are not known to pose a threat (current or historical) to
Climate Change Effects on Individuals
As discussed above in Factor A, climate change can result in detrimental impacts to
Other Sources of Direct and Indirect Mortality
Direct and indirect mortality of
Trampling and collapse of rodent burrows by recreationists, pets, and vehicles could lead to direct mortality of terrestrial life stages of the
Fire management practices over the last century have created the potential for severe fires in the
USFS et al. (2009, p. 74) suggested that the negative effects of roads that have been documented in other amphibians, in concert with the substantial road network across a portion of the
Toads could potentially be trampled or crushed by activities implemented to reduce fire danger. USFS et al. (2009, p. 53) report that
Collectively, direct mortality from land uses within the
Small Population Size
Although it is believed that the range of the
Traill et al. (2009, p. 32) argued for a benchmark viable population size of 5,000 adult individuals (and 500 to prevent inbreeding) for a broad range of taxa, although this type of blanket figure has been disputed as an approach to conservation (Flather et al. 2011, pp. 307-308). Another estimate, specific to amphibians, is that populations of at least 100 individuals are less susceptible to demographic stochasticity (Schad 2007, p. 10). Amphibian species with highly fluctuating population size, high frequencies of local extinctions, and living in changeable environments may be especially susceptible to curtailment of dispersal and restriction of habitat (Green 2003, p. 331). These conditions are all likely applicable to the
Therefore, based on the best available commercial and scientific information, we conclude that small population size is a prevalent and significant threat to the species viability of the
Cumulative Impacts of Extant Threats
Interactive effects or cumulative impacts from multiple additive stressors acting upon
Disease has been documented in
Given the evidence supporting the role of climate in reducing populations and potentially leading to the extirpation of many of the populations studied through the 1970s and into the early 1990s (Kagarise Sherman and Morton 1993, pp. 186-198), this factor is likely either a primary driver, or at least a significant contributing factor in the declines that have been observed. Climate models predict increasing drought intensity and changes to the hydroperiod based on reduced snowpack, along with greater climate variability in the future (PRBO 2011, pp. 18-25). These changes will likely exacerbate stress to the habitat specialist
Determination for Yosemite Toad
Section 4 of the Act (16 U.S.C. 1533), and its implementing regulations at 50 CFR part 424, set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, we may list a species based on (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) Overutilization for commercial, recreational, scientific, or educational purposes; (C) Disease or predation; (D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination.
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the
Yosemite toad populations are subject to threats from habitat degradation associated with land uses that negatively influence meadow hydrology, fostering meadow dewatering, and conifer and other invasive plant encroachment. These activities include the legacy effects of historic grazing activities, the fire management regime of the past century, historic timber management activities, and associated road construction. The impacts from these threats are cumulatively of moderate magnitude, and their legacy impacts on meadow habitats act as a constraint upon extant populations now and are expected to hinder persistence and recovery into the future. Diseases are threats of conservation concern that have likely also had an effect on populations leading to historical population decline, and these threats are operating currently and will continue to do so into the future, likely with impacts of moderate-magnitude effects on
The individual, interactive, and cumulative effects of these various risk factors have acted to reduce the geographic extent and abundance of this species throughout its habitat in the
The Act defines an endangered species as any species that is "in danger of extinction throughout all or a significant portion of its range" and a threatened species as any species "that is likely to become endangered throughout all or a significant portion of its range within the foreseeable future." We find that the
We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the species, and have determined that the
The term "threatened species" means any species (or subspecies or, for vertebrates, distinct population segments) that is likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range. The Act does not define the term "foreseeable future" but it likely describes the extent to which the Service could reasonably rely on predictions about the future in making determinations about the future conservation status of the species. In considering the foreseeable future as it relates to the status of the
Under the Act and our implementing regulations, a species may warrant listing if it is endangered or threatened throughout all or a significant portion of its range. The Yosemite toad is highly restricted in its range, and the threats occur throughout its range. Therefore, we assessed the status of the species throughout its entire range. The threats to the survival of the species occur throughout the species' range and are not restricted to any particular significant portion of that range, nor are they concentrated in a specific portion of the range. Accordingly, our assessment and final determination applies to the species throughout its entire range.
Summary of Comments
In the proposed rule published on
Peer Reviewer Comments
In accordance with our peer review policy published on
We reviewed all comments received from the peer reviewers for substantive issues and new information regarding the listing of the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad. The peer reviewers generally concurred with our methods and conclusions and provided additional information, clarifications, and suggestions to improve the final rule. However, one of the four peer reviewers suggested the rationale for listing Yosemite toad was poorly supported. Peer reviewer comments are addressed in the following summary and incorporated into the final rule.
(1) Comment: Two peer reviewers recommended that we refer to Rana muscosa as the southern mountain yellow-legged frog in order to reduce reader confusion in the final rule.
Our Response: We have clarified the common names we are using in this final rule for each yellow-legged frog species (see Background and Taxonomy sections in this final rule). While Crother et al. (2008, p. 11) accepted the common name of southern mountain yellow-legged frog for Rana muscosa, the use of this common name may create additional confusion as the reader may interpret the name to imply the yellow-legged frogs in southern California that are already listed as the southern DPS, rather than the R. muscosa in the Sierra Nevada. Therefore, we continue to refer to the northern DPS of Rana muscosa as the northern DPS of the mountain yellow-legged frog, as we did in the proposed rule, to minimize confusion for the public.
(2) Comment: Two peer reviewers suggested that we utilize a rangewide analysis for listing Rana muscosa and thereby combine the northern and southern DPSs of the mountain yellow-legged frog into one listed entity. Clarifying discussions with one peer reviewer suggested that we not complete a rangewide analysis, but rather keep the DPSs separate (Knapp, pers. comm.).
Our Response: Given the geographic isolation, different habitat requirements, differences in threats, and different management needs between Rana muscosa in the Sierra Nevada compared with southern California, we have decided to retain the DPS analysis in the proposed rule and to maintain the northern and southern DPSs of mountain yellow-legged frog as separate listed entities. Within the Sierra Nevada, R. muscosa is predominantly found within high-elevation lake habitats that freeze during the winter months, while in southern California, Rana muscosa populations occupy stream habitats that are not typically subject to winter freezing. The differences in the habitats utilized by the northern and southern DPSs of the mountain yellow-legged frog and the differences in the threats to each population segment indicate that management actions needed to recover the northern California and southern California populations will also be different and are most expediently addressed separately by DPS (see Distinct Vertebrate Population Segment Analysis in this final rule).
The factors that are threats to the species also differ between the two DPSs. We have identified fish stocking and presence of fish as a threat for both the northern and southern DPSs. However, the other threats we identified for the northern DPS are primarily habitat degradation, disease, and climate change, whereas the main threats for the southern DPS consist of recreational activities, roads, and wildfire. While there is some overlap in the threats identified for the two DPSs, the threats that are important to the species status vary substantially between the Sierra Nevada and southern California.
The differences between the northern and southern DPSs of the mountain yellow-legged frog in both habitat use and the factors affecting the species results in differences in the actions and activities that would be needed to conserve the species in each of the two DPSs. Conservation planning, including identifying actions and setting priorities for recovery, will be more effective and better suited to meet the species' needs if two separate DPSs are retained.
(3) Comment: One peer reviewer indicated that the frogs within the Spanish and
Our Response: We acknowledge and understand some of the challenges in correctly identifying the species in areas where the ranges of Sierra Nevada and foothill yellow-legged frogs overlap. Recent genetic analysis of samples collected from frogs in Spanish and Bean Creeks has identified the frogs occurring in
While it is not clear whether Wengert (2008) studied Sierra Nevada or foothill yellow-legged frogs, given the stream-based ecological setting of the study, we expect that the movement distances recorded are applicable to the Sierra Nevada yellow-legged frog within a stream-based system, as the ecology is comparable between the two sister taxa in regard to stream systems. Additionally, a study conducted by Fellers et al. (2013, p. 159) documented Sierra Nevada yellow-legged frog movement distances up to 1,032 m in a 29-day period, suggesting the season-long movement distance documented by Wengert (2008, p. 20) is applicable.
(4) Comment: One peer reviewer provided comment that our proposed rule did not include more-recent literature on the effects of airborne contaminants on the mountain yellow legged frog, including Bradford et al. 2011, which measured contaminant concentrations at multiple sites in the southern Sierra Nevada and compared their distribution with population declines of mountain yellow-legged frogs, finding no association between the two. The peer reviewer further recommended that we state that frogs are sensitive to contaminants, but measured contaminant concentrations in multiple media indicate very low exposures to contaminants from upwind sources.
Our Response: In our proposed rule, we included a discussion of environmental factors that affect the mountain yellow-legged frog complex, including contaminants. Based on our analysis in the proposed rule, we did not identify this environmental factor as a threat to the species. Upon our review of additional literature, including a study focused specifically on the mountain yellow-legged frog complex, our initial discussion remains valid, which indicated that the potential threat posed by contaminants is not a factor in the listing of this species. We refer to the proposed rule for the discussion of the effects of contaminants on the mountain yellow-legged frog.
(5) Comment: One peer reviewer suggested that recent genetic studies (Shaffer et al. 2000, Stevens 2001, and Goebel et al. 2009) do not support our conclusion that Yosemite toad is a valid species.
Our Response: When conducting our review of the Yosemite toad as a listable entity under the Act, we incorporated the results of the studies mentioned by the peer reviewer. In addition to the previously included literature on the genetics of Yosemite toad, we have included in this final rule results from Switzer et al. (2009), which provide genetic data supporting the Yosemite toad as a valid species. While we acknowledge that the evolutionary history of the Yosemite toad is complicated and not fully understood, given our conclusions after reviewing the taxonomy of the species, and given that the scientific community as a whole continues to recognize the Yosemite toad as a valid species, we continue to recognize Yosemite toad as a valid species (for further discussion, see Taxonomy section above).
(6) Comment: One peer reviewer provided information regarding the number of localities of Yosemite toad within two National Parks, and suggested that, had we included these locations, the analysis may have had a different outcome.
Our Response: When we conducted our analysis for the proposed rule to determine whether the Yosemite toad warrants listing under the Act, we utilized the best available scientific and commercial information. Part of that information included the geospatial data for Yosemite toad locations within both Yosemite and Sequoia National Parks. These data were subsequently used for the proposed critical habitat designation. While we did have (and used) the information on Yosemite toad locations within the National Parks in our analysis, we did not cite to this information into the text of the proposed rule. This was updated with the data included in Berlow et al. (2013), as well as information received from
(7) Comment: One peer reviewer stated that there is scant evidence available to argue that there has been a decline in abundance of the Yosemite toad and that the difficulty in accurately quantifying toad abundance, coupled with the fact that the proposed rule did not include locality data from the National Parks, has weakened the argument for our determination.
Our Response: While we agree that no studies have documented a rangewide decline in population abundances in Yosemite toads, and we do not have sufficient data to conduct a robust trend analysis or detect negative population growth rates, we relied on published literature for our determination. At a minimum, the published literature provides anecdotally documented declines in numbers of individual Yosemite toads at the respective study sites. The best available information shows that the Yosemite toad populations have declined, and that the remnant populations comprise low numbers of individual adult toads. For our analysis, we did utilize the data on toad locations in the National Parks (see our response to comment 6) and included it as part of our analysis on the estimated loss of historically occupied sites (47-69 percent of formerly occupied sites (Berlow et al. 2013, p. 2)). We mainly focused our analysis on the potential drivers of population stability and identified the predominate threats to the species as the continuing effects of degradation of meadow hydrology associated with historical land management practices and the effects of climate change and anthropogenic stressors acting on the small remnant populations. (For complete discussion see Summary of Factors Affecting the Species section above.)
(8) Comment: One peer reviewer stated that there are scientific uncertainties regarding the long-term population trends and threats to Yosemite toad and that these uncertainties should be explicitly described.
Our response: As required by the Act, we based our proposed rule and this final rule on the best available scientific and commercial data. While there are some uncertainties in the information, we clearly articulated these uncertainties when conducting our analysis for the rule. (See Population Estimate and Status and Meadow Habitat Loss and Degradation sections for examples.)
Federal Agency Comments
(9) Comment: The Forest Service suggested that the rule does not represent the best available scientific and commercial information in proposing a determination.
Our Response: In conducting our analysis, we rely on the best available scientific and commercial information, as required by the Act. On occasion, we are not aware of certain information that is available at the time we issue a proposed rule or new information becomes available around the time of publication, which is part of the reason we request public comment, as well as peer review. That portion of the process helps to inform our final decision by soliciting input and seeking additional available information. As a result of this process, we have received new scientific and commercial information that we have reviewed and incorporated into this final rule.
(10) Comment: The USFS noted that the proposed rule did not identify mining activities as a threat to the mountain yellow-legged frog.
Our Response: We acknowledge that there is some overlap between current mining activities and areas occupied by the mountain yellow-legged frogs, particularly in the northern part of the range; however, we do not have information to assess the impact that mining has on the species in those areas where mining occurs, and how it acts as either an historical or current threat to the species. Within designated wilderness, new mining claims have been prohibited since
(11) Comment: The USFS suggested that the uncertainties we presented under Factor D as it relates to their Forest Plan revision process and protections for mountain yellow-legged frog are not applicable and that the protections under the SNFPA will continue as a result of consultation with the Service.
Our Response: We did not identify Factor D as a threat to the mountain yellow-legged frog, and we incorporated an analysis of the protection that the current Forest Plans offer the species. While there is some uncertainty as to whether these protections will remain in the revised Forest Plans, the USFS is not required to consult with the Service on the Sierra Nevada yellow-legged frog and northern DPS of the mountain yellow-legged frog in the absence of the protections afforded under the Act. As such, we must evaluate the adequacy of existing regulatory mechanisms from the baseline of the species not being federally listed under the Act.
(12) Comment: The USFS suggested the final rule include a discussion of the impacts of bullfrog predation on the mountain yellow-legged frog.
Our Response: We have limited information on the presence of bullfrogs in the Sierra Nevada, but we have included a section on the potential threat of American bullfrogs where they are known to occur in the
(13) Comment: The USFS and several other commenters suggested that the information presented as it relates to the impacts of grazing on Yosemite toad was inaccurate. Specifically, they suggested that we did not include the results of peer-reviewed journal articles in our analysis of the impacts posed by livestock grazing.
Our Response: At the time of the proposed rule, we were aware of the peer-reviewed literature related to the impacts of livestock grazing on Yosemite toad, and inadvertently omitted the literature from the rule. We have reviewed and included the relevant articles in this final rule. Additionally, while we did not incorporate all of the specifics of the journal articles, we did incorporate the results of a 5-year study that investigated the impacts of cattle grazing on Yosemite toad in our analysis, as they were presented in Allen Diaz et al. 2010, and subsequently in the Lind et al. (2011b, addendum).
(14) Comment: The USFS and several other commenters suggested that our reliance on a single non-peer-reviewed study to assess the impacts of cattle grazing on Yosemite toads, through direct mortality or the modification of their habitat, was inappropriate. Additionally, they suggested we discounted the peer-reviewed published journal articles related to the impacts of cattle grazing on Yosemite toad.
Our Response: In conducting our analysis, we rely on the best available scientific and commercial information, as required by the Act. This information does not need to be specifically published in a scientific journal. The Martin (2008) study that is being referred to by the commenters is a doctoral dissertation that was, in fact, reviewed prior to release. We relied on the information presented by Martin in assessing the potential for direct mortality of Yosemite toad that is attributed to livestock. We also relied on Martin for the potential impacts of livestock grazing on overwintering and upland areas utilized by Yosemite toad, as the peer-reviewed publications that the commenters referred to were based on a study that only assessed grazing effects on breeding. As such, the best available scientific and commercial information includes Martin (2008). In our proposed rule, we evaluated the information that ran contrary to Martin (2008), and we have subsequently incorporated the information presented in the peer-reviewed journal articles in this final rule. Please also see response to comment #13.
(15) Comment: The USFS commented that chytrid fungus, fish stocking, and climate change pose the greatest threats to the mountain yellow-legged frogs, and that threats from authorized management activities are insignificant threats to the species.
Our Response: We have concluded in this final rule that, in general, authorized activities on public lands managed by the USFS and the NPS are not significant threats to the mountain yellow-legged frogs, but we also recognize that there may be limited site-specific conditions where authorized activities could have population-level effects, especially where populations are small or habitat areas are limited (see Summary of Factors Affecting the Species in this final rule).
(16) Comment: The USFS noted that recent publications indicate that livestock grazing that meets current USFS standards and guidelines is less of a threat to the Yosemite toad than was described in the proposed rule.
Our Response: We have revised our discussion of grazing in this final rule to clarify the conditions under which we consider current grazing activities to pose habitat-related threats to the Yosemite toad (see Summary of Changes and Factor A discussion for the Yosemite toad).
Comments From States
(17) Comment:
Our Response: We find that an endangered status for the Sierra Nevada yellow-legged frog is an appropriate determination and appreciate CDFW's reconsideration of their initial comments.
(18) Comment: CDFW commented that they remain concerned that listing the species as endangered could hinder timely implementation of the Department's recovery and restoration efforts for the species pursuant to its State-listing under CESA. CDFW notes that they have a responsibility to continue activities and expand efforts that will contribute to the recovery of the Sierra Nevada yellow-legged frog and hope that such efforts can be fostered through the 1991 Cooperative Agreement between the
Our Response: We note that, for research activities that aid in the recovery of the species, and that may result in take, a permit issued under section 10a(1)A of the Act is the appropriate mechanism. However, our regulations at 50 CFR 17.21 state that any qualified employee or agent who is designated by CDFW for such purposes, may, when acting in the course of his official duties, take endangered wildlife species covered by a Cooperative Agreement (developed pursuant to Section 6 of the Act) between the Service and the State provided such take is not reasonably anticipated to result in: (1) The death or permanent disabling of the specimen; (2) the removal of the specimen from the State of California; (3) the introduction of the specimen or any of its progeny into an area beyond the historical range of the species; or (4) the holding of the specimen in captivity for a period of more than 45 days. Take that does not meet these four conditions would require a section 10(a)(1)(A) permit. We acknowledge and appreciate the important role that CDFW will play in the recovery of the Sierra Nevada yellow-legged frog, and look forward to continuing collaborative conservation actions with CDFW for this and other listed species in California.
(19) Comment: CDFW agreed that we should retain the northern DPS and the southern DPS designations for the mountain yellow-legged frog (Rana muscosa). They provided updates to our discussion of take related to State-listing of the mountain yellow-legged frog complex.
Our Response: We appreciate the support, and we have retained the two DPSs in the final determination (see Distinct Vertebrate Population Segment Analysis). We have also revised our discussion of CESA to provide the updated information on take related to State-listing of the mountain yellow-legged frog complex (see Factor D for mountain yellow-legged frog).
(20) Comment: CDFW provided comments on our discussion of the following threats to the mountain yellow-legged frog complex: Recreational activities, past trout stocking versus continued trout stocking, and pesticide detection in the Sierra Nevada. They commented that the evidence presented in the Recreation section did not support the conclusion, urging us to readdress the section and remove claims unsupported by appropriate citations, and noted that recreation effects to the environment were supported, but no evidence indicates that such activities affect the frog populations. In the Recreation section, they also noted several errors and inaccuracies in citing other authors. CDFW provided extensive comments on our discussion of dams and water diversions, commenting that they were of the opinion that dams and diversion posed a threat of low significance to the continued existence of the mountain yellow-legged frogs and suggesting that the section required significant amendments to accurately capture the degree of potential impacts. They noted that most dams were constructed below the range of extant frog populations, and that some information was misapplied from research on lower-elevation amphibian species, such as the foothill yellow-legged frog, which resulted in overstatement of the potential impact of dams and water diversions on the mountain yellow-legged frog complex. They provided numerous smaller specific comments on text within the section.
Our Response: We thank the CDFW for the additional information provided to strengthen our analysis. We have addressed these comments through changes to the Fish Stocking, Recreation, and Dams and Water Diversions sections for the Sierra Nevada and mountain yellow-legged frogs in this final rule. We re-checked references and revised the sections noted to state more clearly the potential effects of these activities, to rely on appropriate citations, and to refine our conclusions in agreement with CDFW's comments. Please see Factor A in Summary of Factors Affecting the Species for updated information.
Public Comments
(21) Comment: Several commenters suggested that the Service does not have the authority or jurisdiction to designate the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog as endangered nor the Yosemite toad as threatened.
Our Response: The authority for the Service to issue this rulemaking comes from the Endangered Species Act of 1973 (16 U.S.C.
(22) Comment: Multiple commenters indicated that existing Federal and State legislation and regulations, such as the Wilderness Act, CESA, and CDFW regulations, provide sufficient protection for these amphibians, and thereby eliminate the need for listing the species.
Our Response: We agree that existing Federal and State legislation and regulations, such as the Wilderness Act, CESA, and CDFW regulations provide some protection for the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad. However, while existing legislation and regulations provide some level of protection for the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad, they do not require that Federal agencies ensure that actions that they fund, authorize, or carry out will not likely jeopardize the species' continued existence (for further information see discussions under Factor D). Therefore, we have determined that the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog are endangered and that the Yosemite toad is threatened under the Act.
(23) Comment: Several commenters suggest that it is necessary for the Service to conduct an analysis of the impacts that listing a species may have on local economies prior to issuance of a final rule.
Our Response: Under the Act, the Service is not required to conduct an analysis regarding the economic impact of listing endangered or threatened species. However, the Act does require that the Service consider the economic impacts of a designation of critical habitat. A draft of this analysis is available to the public on http://www.regulations.gov (79 FR 1805).
(24) Comment: Several commenters suggested that the decline of the Sierra Nevada yellow-legged frog, northern DPS of the mountain yellow-legged frog, and the Yosemite toad is a natural evolutionary process, and that the presence of environmental stressors is a normal driver of evolution and/or extinction.
Our Response: Under the Act, we are required to use the best available scientific and commercial information to assess the factors affecting a species in order to make a status determination. The Act requires the Service to consider all threats and impacts that may be responsible for declines as potential listing factors. The evidence presented suggests that the threats to the species are both natural and manmade (see Factor E--Other Natural or Manmade Factors Affecting the Species), but that they are primarily the result of anthropogenic influences (see Summary of Factors Affecting the Species in this final rule). Thus, the threats associated with the declines of these species are not part of a natural evolutionary process.
(25) Comment: Several commenters were concerned about the effects of listing on mining and associated activities conducted under the General Mining Law of 1872. They suggested that the listing of these species will remove 5 million acres from mining and other productive uses of the land. One commenter was concerned that there would be no assurances that development of a mining claim will result in the ability to mine it.
Our Response: In the proposed rule, we identified unauthorized discharge of chemicals or fill material into any water upon which the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad are known to occur as a potential threat to these species. On National Forests outside of designated wilderness, new mining may occur pursuant to the Mining Law of 1872 (30 U.S.C. 21 et seq.), which was enacted to promote exploration and development of domestic mineral resources, as well as the settlement of the western United States. It permits U.S. citizens and businesses to prospect hardrock (locatable) minerals and, if a valuable deposit is found, file a claim giving them the right to use the land for mining activities and sell the minerals extracted, without having to pay the Federal Government any holding fees or royalties (GAO 1989, p. 2). Gold and other minerals are frequently mined as locatable minerals, and, as such, mining is subject to the Mining Law of 1872. However, Federal wilderness areas were closed to new mining claims at the beginning of 1984 (see Factor D under mountain yellow-legged frogs above), thereby precluding the filing of new mining claims in those areas designated as Federal wilderness (a large part of the area in which the species occur). Authorization of mining under the Mining Law of 1872 is a discretionary agency action pursuant to section 7 of the Act. Therefore, Federal agencies with jurisdiction over land where mining occurs will review mining and other actions that they fund, authorize, or carry out to determine if listed species may be affected in accordance with section 7 of the Act.
(26) Comment: Numerous commenters suggested that the listing of the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad are being misused to restrict or prohibit access for fishing, hiking, camping, and other recreational uses, and implement land use restrictions, management requirements, and personal liabilities on the public that are not prudent, clearly defined, or necessary.
Our Response: The listing of the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad does not prevent access to any land, whether private, tribal, State, or Federal. The listing of a species does not affect land ownership or establish a refuge, wilderness, reserve, or other conservation area. A listing does not allow the government or public to access private lands without the permission of the landowner. It does not require implementation of restoration, recovery, or enhancement measures by non-Federal landowners. Federal agencies will review actions that they fund, authorize, or carry out to determine if any of these three amphibians, and other listed species as appropriate, may be affected by the Federal action. The Federal agency will consult with the Service, in accordance with Section 7 of the Act (see also response to comment 25).
(27) Comment: Several commenters suggested that listing the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog under the Act is not necessary given that a majority of the range of these species is within wilderness areas afforded protection under the Wilderness Act and by the protections afforded under CESA.
Our Response: We agree that existing Federal and State legislation and regulations, such as the Wilderness Act and CESA, provide some protection for the Sierra Nevada mountain yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad. However, we identified the main threats to the two frog species as habitat degradation and fragmentation, predation and disease, climate change, and the interactions of these stressors on small populations. Neither the Wilderness Act nor the State's listing status under CESA ameliorates these threats to levels that would preclude the need to list the species under the Act. (See discussion under Factor D).
(28) Comment: One commenter suggested that habitat and range of the mountain yellow-legged frog is not threatened with destruction or modification based on a large portion being located in wilderness, and the proposed rule stating "physical habitat destruction does not appear to be the primary factor associated with the decline of the mountain yellow-legged frogs."
Our Response: While we agree that the loss, destruction, or conversion of physical habitat is not a primary factor in the decline of the mountain yellow-legged frogs, we discuss both the biological modification of habitat due to changes in predator communities, prey communities, and in nutrient levels, and due to the habitat fragmentation associated with the presence of introduced fish. Although the presence of introduced fish does not result in conversion or loss of the physical attributes of habitat (for example, removal or filling of lakes, ponds, etc.), fish presence does effectively preclude the use of the habitat by the mountain yellow-legged frog (see our discussion under Factor A). While a large portion of the range of the mountain yellow-legged frog is within federally designated wilderness, or on National Parks, we identified the main threats to the species as habitat degradation and fragmentation, predation and disease, climate change, and the interactions of these stressors on small populations. Neither the Wilderness Act nor the protections afforded within National Parks ameliorates these threats to levels that would preclude the need to list the species under the Act (see discussion under Factor D).
(29) Comment: One commenter stated that we failed to consider the effectiveness of restoration activities being conducted by CDFW as part of their
Our Response: We are aware of the activities, including the
(30) Comment: One commenter provided information suggesting livestock are responsible for the transportation of Bd in the environment.
Our Response: While livestock may provide a vector for the transmission of amphibian disease within the Sierra Nevada, there are numerous other mechanisms of transport, including wildlife, as well as anthropogenic vectors. Since the importance of differing disease vectors related to Bd is poorly understood, we did not include a discussion of disease transport associated with livestock grazing in this rule (see Factor C for discussion of disease).
(31) Comment: One commenter provided information to suggest that activities associated with illicit cultivation of marijuana on National Forest System lands should be identified as a potential threat to the mountain yellow-legged frog.
Our Response: We agree that aspects associated with illegal cultivation of marijuana on National Forest System lands may pose a risk to the mountain yellow-legged frogs, such as dewatering of habitats and contamination from pesticides and fertilizers. There is potential overlap with this illegal activity and areas occupied by mountain yellow-legged frogs; however, not enough information is available at this point to assess the impact that illegal cultivation of marijuana has on the species.
(32) Comment: Several commenters suggest that there is insufficient evidence to make a listing determination for the mountain yellow-legged frog in accordance with the Act.
Our Response: As we have presented in both the proposed rule and this final rule, a substantial compilation of scientific and commercial information is available to support listing both the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog under the Act. We have presented evidence that there has been a curtailment in range and numbers attributed to habitat degradation and fragmentation under Factor A, predation and disease under Factor C, and climate change and the interaction of these various stressors cumulatively impacting small remnant populations under Factor E (see Determination for the Sierra Nevada Yellow-legged Frog and Determination for the Northern DPS of the Mountain Yellow-legged Frog sections above for a synopsis and see the Summary of Factors Affecting the Species for a detailed analysis).
(33) Comment: Numerous commenters purported that the greatest threat to the mountain yellow-legged frog is Bd, and since listing the species will not alleviate the threat, the species should not be listed. Additionally, it was suggested that these species should be reared in captivity until the threat of Bd is resolved.
Our Response: We agree that Bd is one of the primary contributing factors in the current decline of these species; however, it is not the only factor responsible for their decline or the only one forming the basis of our determination. All Factors are considered when making a listing determination (see the Summary of Factors Affecting the Species for a detailed discussion). We have also identified habitat fragmentation and predation attributed to the introduction of fish and climate change as threats to the species. We are required to evaluate all the threats affecting a species, including disease under Factor C.
With respect to the prospect of captive breeding, we acknowledge that this activity is one of the suite of tools that can be utilized for the conservation of the species. Captive breeding is currently being conducted for the southern DPS of the mountain yellow- legged frog, and we are currently working with various facilities to explore this option. Additionally, when a species is listed as either endangered or threatened, the Act provides many tools to advance the conservation of listed species; available tools including recovery planning under section 4 of the Act, interagency cooperation and consultation under section 7 of the Act, and grants to the States under section 6 of the Act. All of these mechanisms assist in the conservation of the species.
(34) Comment: Several commenters provided information to suggest that livestock grazing is not detrimental to amphibian species and that the proposed rule did not adequately capture the neutral or beneficial effects of livestock grazing on amphibian species.
Our Response: We have revised our discussion of grazing in this final rule to clarify the conditions under which we consider current grazing activities to pose habitat-related threats (see Factor A above). In addition, research with a related ranid frog of western montane environments, (the Columbia spotted frog, Rana luteiventris) has indicated that livestock grazing may reduce vegetation levels in riparian and wet meadow habitat, but does not have short-term effects on the frog populations, although they caution that the length of the study may not capture potential long-term effects (Adams et al. 2009, pp. 132, 137). However, George et al. (2011, pp. 216, 232) in a review of the effectiveness of management actions on riparian areas, noted that continuous grazing often results in heavy grazing use of riparian areas, even if an area is lightly stocked, because livestock are attracted to the areas from adjacent uplands. They note substantial literature that documents that livestock grazing could damage riparian areas, and the resulting move, beginning in the 1980s, in Federal and State resource agencies to apply conservation practices to protecting and improving riparian habitats (George et al. 2011, p. 217). They note that studies provide sufficient evidence that riparian grazing management that maintains or enhances key vegetation attributes will enhance stream channel and riparian soil stability, although variable biotic and abiotic conditions can have site-specific effects on results (George et al. 2011, pp. 217-227).
In our proposed rule, we focused on livestock grazing as a potential listing factor, and while there are potentially some current, localized effects to the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, and the Yosemite toad, we consider the majority of the impacts associated with livestock grazing are the legacy effects of historically high grazing intensities.
(35) Comment: One commenter stated that the discussion of the effects of global climate change in the proposed rule for the Sierra Nevada yellow-legged frog, northern DPS of the mountain yellow-legged frog, and Yosemite toad was not appropriate. The commenter believed that the Service "pushes" the climate models, both spatially and temporally, beyond what the commenter considered to be reliable, and ignores their uncertainty. In addition, the commenter claims that no credible models can project potential climate change in the Sierra Nevada. The commenter stated the Act is not an appropriate mechanism to regulate global climate change and greenhouse gases. Finally, the commenter suggested if the Service does list the three amphibians, that they be designated as threatened species with a section 4(d) rule that excludes lawful greenhouse gases from the prohibitions of the Act.
Our Response: We used the best available scientific and commercial information available as it pertains to climate change. In addition to the peer-reviewed scientific journal articles and reports that were utilized in our analysis and cited in the proposed rule, recently published studies have presented data and conclusions that increase the level of confidence that global climate change is the result of anthropogenic actions (summarized in Blaustein et al. 2010 and discussed above). A recent paper (Kadir et al. 2013) provides specific information on the effects of climate change in the Sierra Nevada and is discussed above. While the Service is concerned about the effects of global climate change on listed species, wildlife, and their habitats, to date, we have not used the Act to regulate greenhouse gases. We evaluated the suggestion that the three amphibians be listed as threatened species with a section 4(d) rule excluding prohibitions or restrictions on greenhouse gases. However, our determination is that the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog meet the definition of endangered, the Yosemite toad meets the definition of threatened, and a section 4(d) rule for greenhouse gases is not appropriate.
(36) Comment: One commenter suggested that the discussion of genetics for the mountain yellow-legged frog does not support the taxonomy of the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog as separate species. The commenter further suggested the text of the rule specifying two major genetic lineages and four groups does not support listing of the frogs as separate genetic groups.
Our Response: Vredenburg et al. (2007, p. 317) did not rely solely on DNA evidence in the recognition of two distinct species of mountain yellow-legged frog in the Sierra Nevada, but instead used a combination of DNA evidence, morphological information, and acoustic studies. The taxonomy of the mountain yellow-legged frogs as two distinct species in the Sierras has been widely accepted in the scientific community and by species experts. We are not listing a subspecies but rather two separate, recognized species, the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog.
(37) Comment: Several commenters suggested that activities such as timber harvest, road construction, recreation, and livestock grazing are in decline in the Sierras compared with historical levels and should not be included as potential threats to the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, or the Yosemite toad.
Our Response: In conducting our analysis of the factors affecting the species, we did include timber harvest, road construction, recreation, and livestock grazing, as potential threats to the species, but acknowledge that the major impact on the species was the result of the legacy effects of historical practices, and that these activities currently pose a lower intensity, localized threat. We have attempted to clarify the distinction in this final rule (see Factor A discussions above).
(38) Comment: Numerous commenters stated that listing the mountain yellow-legged frogs and the Yosemite toad would prevent fuels-reduction activities, leading to fires and loss of habitat.
Our Response: In this final rule under Factor A for the mountain yellow-legged frogs and Yosemite toad, we address potential habitat changes that may be related to timber harvest activities, including harvests for fuels reduction purposes. We found that most populations of the three species occur at high elevations above areas where timber harvests are likely. At lower elevations, forest standards and guidelines would be expected to limit potential threats to the species in most cases, although limited site-specific situations might result in habitat effects with population consequences. We also found that changed fire regimes have, in some of the same lower elevation areas, led to an increased potential for high-intensity fires, which could alter habitat and, therefore, pose relatively localized population-level effects to the species. For the Yosemite toad, we found that although ground-disturbance due to timber harvest activities has the potential to have population-level effects at lower elevations, especially where habitat is limited, currently the best available information indicates toads might achieve long-term benefits from activities that reduce encroachment of trees into breeding sites. Therefore, we expect that fuels-reduction activities in lower elevation areas will be generally beneficial to these species.
(39) Comment: A number of commenters suggested that, given the results of more-recent studies that were not included in the proposed rule, livestock grazing should be removed as a threat to the Yosemite toad (See also comment 13 from the USFS).
Our Response: In our proposed rule, we addressed the potential impacts of grazing on Yosemite toad based on Allen-Diaz et al. (2010). The more-recent studies referenced (such as Roche et al. 2012a and 2012b, and McIlroy et al. 2013) are different publications but are based on the results of the companion studies whose initial report, and subsequent addendum, we referenced as Allen-Diaz et al. (2010) and Lind et al. (2011b). The study conducted determined that livestock grazing in accordance with the USFS's standards and guidelines does not affect Yosemite toad breeding success. While appropriately managed levels of grazing do not impact breeding success, these grazing standards are not always met. Additionally, the main impact of grazing on Yosemite toad is due to the legacy effects of historical grazing intensities on Yosemite toad habitat. Given the limitations of the study (see discussion under Factor A) and the documentation that these standards are not always met, livestock grazing may continue to pose a localized threat to the species.
(40) Comment: One commenter provided several comments suggesting that livestock grazing is not a threat to Yosemite toad in light of the results of a current study, the documentation of Yosemite toads existing in areas that have been subject to grazing for centuries, and because the population declines cited in our proposed rule occurred in an area not subject to grazing.
Our Response: See response to comments 13, 14, and 39. In our proposed rule, we identified the impacts of livestock grazing primarily from an historical context as a potential contributor to meadow degradation. There is a great deal of information, while not specific to Yosemite toad, on the negative impacts of high-intensity grazing regimes on ecosystem dynamics. Grazing under current
(41) Comment: One commenter suggested that livestock grazing continues to provide a threat to the Sierra Nevada yellow-legged frog and Yosemite toad and provided information documenting habitat degradation attributed to current livestock grazing and utilization above the standards of the SNFPA.
Our Response: As we have presented in the proposed and final rules, the impact of livestock grazing on these species is primarily one of historical significance, with the potential for future localized impacts to the species and/or their habitat. Based on the information provided regarding habitat conditions and potential impacts to habitat, we have maintained our position that current livestock grazing poses a localized impact to the mountain yellow-legged frogs and a prevalent threat with moderate impacts to the Yosemite toad.
(42) Comment: One party commented that we have not demonstrated that the Sierra Nevada population of the mountain yellow-legged frog is a DPS. They indicate that we have not shown that the population is significant to the taxon as a whole because we have not shown whether other populations of the species could persist in the high-elevation Sierra Nevada portion of the species' range or discussed how the Sierra Nevada populations are adapted to the area. In addition, they indicate that we failed to show that extirpation of the northern population would result in a significant gap in the range of the species, and we did not show that the populations had markedly different genetics characteristics.
Our Response: The commenters correctly noted that, to recognize a population of a species as a DPS, we must establish that the population is (1) discrete from the remainder of the populations to which the species belongs, and (2) if determined to be discrete, it is also found to be significant to the species to which it belongs. However, the commenters incorrectly conclude that the population must meet all three criteria for significance. We find the northern population of the mountain yellow-legged frog to be discrete from the southern population because it is separated from the southern frogs by a 225-km (140-mi) barrier of unsuitable habitat. The primary basis for our finding that the northern population is significant to the species as a whole is that loss of the northern population would mean the loss of the species from a large portion of its range and reduce the species to small isolated occurrences in southern California. The population also meets two additional criteria for significance: (1) Evidence of the persistence of the discrete population segment in an ecological setting unusual or unique for the taxon, and (2) evidence that the discrete population segment differs markedly from the remainder of the species in its genetic characteristics. We have revised the language in our DPS analysis to clarify the basis for the determination (see Distinct Vertebrate Population Segment Analysis).
(43) Comment: Numerous commenters commented that we were required to complete a NEPA analysis of the proposed listing.
Our Response: We have determined that environmental assessments and environmental impact statements, as defined under the authority of the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be prepared in connection with listing a species as an endangered or threatened species under the Endangered Species Act. We published a notice outlining our reasons for this determination in the
(44) Comment: One commenter asked that, if we determine that the three amphibian species under consideration are endangered or threatened under the Act, then we enter into a cooperative agreement with the State of California under section 6 of the Act.
Our Response: We have been operating under such a cooperative agreement with the California Department of Fish and Game (now
(45) Comment: One commenter stated that if the three amphibians considered are listed as threatened or endangered, then research should continue into the causes of population decline.
Our Response: We expect research on these issues to continue into the future. Once the three amphibians are listed as threatened or endangered species under the Act, additional funding for research and other conservation programs for those species will become available through grants established under section 6 of the Act. Such grants are provided to State agencies with which we have established cooperative agreements.
(46) Comment: One commenter indicated that because of a County resolution, we must coordinate with the board of supervisors of that County prior to publishing a final rule.
Our Response: We provide all interested parties an equal opportunity to submit comments or information prior to publication of a final rule, and we give equal consideration to all such information and comments, regardless of source. Our requirements for "coordination," however, are established by the Act, by other Federal statutes such as the Administrative Procedure Act, and by executive order.
(47) Comment: Several commenters asked for additional time to provide comments. One commenter added that we provided little public outreach.
Our Response: As discussed in the first paragraph of the Summary of Comments and Recommendations section (above), we provided two additional public comment periods for a total of 240 days (approximately 8 months) of public comment. We also hosted two public hearings and two public informational meetings at various locations within the range of the species under consideration. We also attended two additional public meetings hosted by Congressmen representing districts within the range of the species. We contacted and sought input from appropriate Federal and State agencies, scientific experts and organizations, and other interested parties. We also published notices in the newspapers with the largest readerships within both the northern and southern portions of the ranges of the species. Additional public comment periods or outreach were not feasible given limitations imposed by available funds and requirements imposed by the Act regarding available time in which to publish a final rule.
(48) Comment: One commenter noted that the Act authorizes the Secretary to extend the time available for publication of a final rule by up to 6 months if "there is substantial disagreement regarding the sufficiency or accuracy of the available data." The commenter stated that such substantial disagreement does exist and so requested that the available time be extended by 6 months. Specifically, the commenter indicated that the available data are not sufficient to support listing after taking into account various Federal and State statutes and programs currently benefiting the three species. Such statutes and programs include the Wilderness Act, the Sierra Nevada Forest Plan, the Clean Water Act, the California Endangered Species Act, and the discontinuation of fish stocking by CDFW in much of the range of the two frogs.
Our Response: While we agree that these efforts aid in the conservation of the three amphibians, we do not consider substantial disagreement to exist regarding our conclusion that the Sierra Nevada yellow-legged frog and the northern DPS of the mountain yellow-legged frog meet the definition of "endangered species" under the Act. We considered the existing Federal and State statutes and programs in our determination. The data documenting population declines and extirpations associated with Bd and the presence of introduced fish are sufficient for the Service to determine that the two species are "in danger of extinction throughout all or a significant portion of [their] range[s]." Data also show that the Yosemite toad is vulnerable to habitat changes and climate change, and thus merits listing as a threatened species, which is defined as "likely to become an endangered species within the foreseeable future within all or a significant portion of its range."
Available Conservation Measures
Conservation measures provided to species listed as endangered or threatened under the Act include recognition, recovery actions, requirements for Federal protection, and prohibitions against certain practices. Recognition through listing results in public awareness, and conservation by Federal, State, Tribal, and local agencies, private organizations, and individuals. The Act encourages cooperation with the States and requires that recovery actions be carried out for all listed species. The protection required by Federal agencies and the prohibitions against certain activities are discussed, in part, below.
The primary purpose of the Act is the conservation of endangered and threatened species and the ecosystems upon which they depend. The ultimate goal of such conservation efforts is the recovery of these listed species, so that they no longer need the protective measures of the Act. Subsection 4(f) of the Act requires the Service to develop and implement recovery plans for the conservation of endangered and threatened species. The recovery planning process involves the identification of actions that are necessary to halt or reverse the species' decline by addressing the threats to its survival and recovery. The goal of this process is to restore listed species to a point where they are secure, self-sustaining, and functioning components of their ecosystems.
Recovery planning includes the development of a recovery outline shortly after a species is listed and preparation of a draft and final recovery plan. The recovery outline guides the immediate implementation of urgent recovery actions and describes the process to be used to develop a recovery plan. Revisions of the plan may be done to address continuing or new threats to the species, as new substantive information becomes available. The recovery plan identifies site-specific management actions that set a trigger for review of the five factors that control whether a species remains endangered or may be downlisted or delisted, and methods for monitoring recovery progress. Recovery plans also establish a framework for agencies to coordinate their recovery efforts and provide estimates of the cost of implementing recovery tasks. Recovery teams (composed of species experts, Federal and State agencies, nongovernmental organizations, and stakeholders) are often established to develop recovery plans. When completed, the recovery outline, draft recovery plan, and the final recovery plan will be available on our Web site (http://www.fws.gov/endangered), or from our Sacramento Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Implementation of recovery actions generally requires the participation of a broad range of partners, including other Federal agencies, States, Tribal, nongovernmental organizations, businesses, and private landowners. Examples of recovery actions include habitat restoration (e.g., restoration of native vegetation), research, captive propagation and reintroduction, and outreach and education. The recovery of many listed species cannot be accomplished solely on Federal lands because their range may occur primarily or solely on non-Federal lands. To achieve recovery of these species requires cooperative conservation efforts on private, State, and Tribal lands.
Following publication of this final listing rule, funding for recovery actions will be available from a variety of sources, including Federal budgets, State programs, and cost share grants for non-Federal landowners, the academic community, and nongovernmental organizations. In addition, pursuant to section 6 of the Act, the States of California and Nevada would be eligible for Federal funds to implement management actions that promote the protection or recovery of the Sierra Nevada mountain yellow-legged frog, Northern Distinct Population Segment of the mountain yellow-legged frog, and the Yosemite toad. Information on our grant programs that are available to aid species recovery can be found at: http://www.fws.gov/grants.
Please let us know if you are interested in participating in recovery efforts for the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, or the Yosemite toad. Additionally, we invite you to submit any new information on these species whenever it becomes available and any information you may have for recovery planning purposes (see FOR FURTHER INFORMATION CONTACT).
Section 7(a) of the Act requires Federal agencies to evaluate their actions with respect to any species that is listed as an endangered or threatened species and with respect to its critical habitat, if any is designated. Regulations implementing this interagency cooperation provision of the Act are codified at 50 CFR part 402. Section 7(a)(2) of the Act requires Federal agencies to ensure that any action authorized, funded or carried out by such agency is not likely to jeopardize the continued existence of the species or destroy or adversely modify its critical habitat. If a Federal action may affect a listed species or its critical habitat, the responsible Federal agency must enter into consultation with the Service.
Federal agency actions within the species' habitat that may require consultation, as described in the preceding paragraph, include management and any other landscape-altering activities on Federal lands administered by the USFS, NPS, and other Federal agencies as appropriate.
The Act and its implementing regulations set forth a series of general prohibitions and exceptions that apply to all endangered and threatened wildlife. The prohibitions of section 9(a)(2) of the Act, codified at 50 CFR 17.21 for endangered wildlife, in part, make it illegal for any person subject to the jurisdiction of the United States to take (includes harass, harm, pursue, hunt, shoot, wound, kill, trap, capture, or collect; or to attempt any of these), import, export, ship in interstate commerce in the course of commercial activity, or sell or offer for sale in interstate or foreign commerce any listed species. Under the Lacey Act (18 U.S.C. 42-43; 16 U.S.C. 3371-3378), it is also illegal to possess, sell, deliver, carry, transport, or ship any such wildlife that has been taken illegally. Certain exceptions apply to agents of the Service and State conservation agencies.
We may issue permits to carry out otherwise prohibited activities involving endangered and threatened wildlife species under certain circumstances. Regulations governing permits are codified at 50 CFR 17.22 for endangered species, and at 17.32 for threatened species. With regard to endangered wildlife, a permit must be issued for the following purposes: for scientific purposes, to enhance the propagation or survival of the species, and for incidental take in connection with otherwise lawful activities.
It is our policy, as published in the
(1) Unauthorized collecting, handling, possessing, selling, delivering, carrying, or transporting of the species, including import or export across State lines and international boundaries, except for properly documented antique specimens of these taxa at least 100 years old, as defined by section 10(h)(1) of the Act;
(2) Introduction of species that compete with or prey upon the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, or the Yosemite toad;
(3) The unauthorized release of biological control agents that attack any life stage of these species;
(4) Unauthorized modification of the mountain meadow habitats or associated upland areas important for the breeding, rearing, and survival of these species; and
(5) Unauthorized discharge of chemicals or fill material into any waters in which the Sierra Nevada yellow-legged frog, the northern DPS of the mountain yellow-legged frog, or the Yosemite toad are known to occur.
Questions regarding whether specific activities would constitute a violation of section 9 of the Act should be directed to the Sacramento Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Under section 4(d) of the ESA, the Secretary has discretion to issue such regulations as he deems necessary and advisable to provide for the conservation of threatened species. Our implementing regulations (50 CFR 17.31) for threatened wildlife generally incorporate the prohibitions of section 9 of the Act for endangered wildlife, except when a "special rule" promulgated pursuant to section 4(d) of the Act has been issued with respect to a particular threatened species. In such a case, the general prohibitions in 50 CFR 17.31 would not apply to that species, and instead, the special rule would define the specific take prohibitions and exceptions that would apply for that particular threatened species, which we consider necessary and advisable to conserve the species. The Secretary also has the discretion to prohibit by regulation with respect to a threatened species any act prohibited by section 9(a)(1) of the ESA. Exercising this discretion, which has been delegated to the Service by the Secretary, the Service has developed general prohibitions that are appropriate for most threatened species in 50 CFR 17.31 and exceptions to those prohibitions in 50 CFR 17.32. Since we are not promulgating a special section 4(d) rule, all of the section 9 prohibitions, including the "take" prohibitions, will apply to the Yosemite toad.
Required Determinations
National Environmental Policy Act (42 U.S.C. 4321 et seq.)
We have determined that environmental assessments and environmental impact statements, as defined under the authority of the National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et seq.), need not be prepared in connection with listing a species as an endangered or threatened species under the Endangered Species Act. We published a notice outlining our reasons for this determination in the
Government-to-Government Relationship With Tribes
In accordance with the President's memorandum of
References Cited
A complete list of references cited in this rulemaking is available on the Internet at http://www.regulations.gov and upon request from the Sacramento Fish and Wildlife Office (see FOR FURTHER INFORMATION CONTACT).
Authors
The primary authors of this final rule are the staff members of the Sacramento Fish and Wildlife Office.
List of Subjects in 50 CFR Part 17
Endangered and threatened species, Exports, Imports, Reporting and recordkeeping requirements, Transportation.
Regulation Promulgation
Accordingly, we amend part 17, subchapter B of chapter I, title 50 of the Code of Federal Regulations, as follows:
PART 17--[AMENDED]
1. The authority citation for part 17 continues to read as follows:
Authority: 16 U.S.C. 1361-1407; 1531-1544; 4201-4245; unless otherwise noted.
2. Amend SEC 17.11(h), the List of Endangered and Threatened Wildlife, by revising the entry for "Frog, mountain yellow-legged (southern California DPS)" and adding entries for "Frog, mountain yellow-legged (northern California DPS)", "Frog, Sierra Nevada yellow-legged", and "Toad, Yosemite" to the List of Endangered and Threatened Wildlife in alphabetical order under Amphibians to read as follows:
SEC 17.11 Endangered and threatened wildlife.
* * * * *
(h) * * *
Species Historic range Vertebrate population where endangered or threatened Common name Scientific name * * * * * * * Amphibians * * * * * * * Frog, mountain Rana muscosa U.S.A. (CA) U.S.A., northern yellow-legged California (northern California DPS) Frog, mountain Rana muscosa U.S.A. (CA) U.S.A., southern yellow-legged California (southern California DPS) * * * * * * * Frog, Sierra Rana sierrae U.S.A. (CA, NV) Entire Nevada yellow- legged * * * * * * * Toad, Yosemite Anaxyrus canorus U.S.A. (CA) Entire * * * * * * *
Species Status When listed Critical Special rules habitat Common name * * * * * * * Amphibians * * * * * * * Frog, mountain E 834 NA NA yellow-legged (northern California DPS) Frog, mountain E 728 17.95(d) NA yellow-legged (southern California DPS) * * * * * * * Frog, Sierra E 834 NA NA Nevada yellow- legged * * * * * * * Toad, Yosemite T 834 NA NA * * * * * * *
* * * * *
Dated:
Daniel M. Ashe,
Director,
[FR Doc. 2014-09488 Filed 4-25-14;
BILLING CODE 4310-55-P
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