# 73 FR 4380: Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Siskiyou Mountains Salamander (Plethodon stormi) and Scott Bar Salamander (Plethodon asupak) as Threatened or Endangered

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URL: https://www.frixlaw.com/law-library/statutes/FR_PRORULE_E8-918

## Section

- **Citation:** 73 FR 4380
- **Heading:** Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Siskiyou Mountains Salamander (Plethodon stormi) and Scott Bar Salamander (Plethodon asupak) as Threatened or Endangered
- **Jurisdiction:** Federal
- **Kind:** Regulations
- **Status:** In force
- **Text as of:** August 14, 2026
- **Source:** Compiled text
- **Location:** Federal Register / Vol. 73 / 73 FR 4380

## Text

DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [FWS-R8-ES-2008-0002; 1111 FY07 MO;ABC Code: B2] Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List the Siskiyou Mountains Salamander (Plethodon stormi) and Scott Bar Salamander (Plethodon asupak) as Threatened or Endangered AGENCY:
Fish and Wildlife Service, Interior.

ACTION:
Notice of 12-month petition finding.

SUMMARY:
We, the U.S. Fish and Wildlife Service (Service), announce a 12-month finding on a petition to list the Siskiyou Mountains salamander ( Plethodon stormi ) and Scott Bar salamander ( Plethodon asupak ) as threatened or endangered, under the Endangered Species Act of 1973, as amended (Act). After a thorough review of all available scientific and commercial information, we find that listing the Siskiyou Mountains salamander and Scott Bar salamander is not warranted. We ask the public to continue to submit to us any new information concerning the status of, and threats to, these species. This information will help us to monitor and encourage the ongoing management of these species.

DATES:
We made the finding announced in this document on January 24, 2008.

ADDRESSES:
This finding is available on the Internet at http://www.regulations.gov and http://www.fws.gov/yreka/. Supporting documentation we used in preparing this finding is available for public inspection, by appointment, during normal business hours at the U.S. Fish and Wildlife Service, Yreka Fish and Wildlife Office, 1829 S. Oregon Street, Yreka, CA 96097; telephone 530-842-5763; facsimile 530-842-4517. Please submit any new information, materials, comments, or questions concerning this finding to the above address or via electronic mail (e-mail) at Siskiyou_salamander@fws.gov .
FOR FURTHER INFORMATION CONTACT:
Phil Detrich, Field Supervisor, U.S. Fish and Wildlife Service, Yreka Fish and Wildlife Office (see ADDRESSES section)
Yreka, CA 96097; telephone 530-842-5763; facsimile 530-842-4517. Please submit any new information, materials, comments, or questions concerning this finding to the above address or via electronic mail (e-mail) at Siskiyou_salamander@fws.gov .
FOR FURTHER INFORMATION CONTACT:
Phil Detrich, Field Supervisor, U.S. Fish and Wildlife Service, Yreka Fish and Wildlife Office (see ADDRESSES section). If you use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires that, for any petition to revise the Lists of Endangered and Threatened Wildlife and Plants that contains substantial scientific and commercial information that listing may be warranted, we make a finding within 12 months of the date of our receipt of the petition on whether the petitioned action is: (a) Not warranted, (b) warranted, or (c) warranted, but the immediate proposal of a regulation implementing the petitioned action is precluded by other pending proposals to determine whether any species is threatened or endangered. Such 12-month findings are to be published promptly in the Federal Register . Section 4(b)(3)(C) of the Act requires that we treat a petition for which the requested action is found to be warranted but precluded as though resubmitted on the date of such finding, and we must make a subsequent finding within 12 months.
Previous Federal Actions
On June 18, 2004, we received a petition dated June 16, 2004, from the Center for Biological Diversity, Klamath-Siskiyou Wildlands Center, and Noah Greenwald, to list the Siskiyou Mountains salamander ( Plethodon stormi ) as a threatened or endangered species on behalf of themselves and five other organizations. The petition clearly identified itself as such and included the requisite identification information for the petitioners, as required in 50 CFR 424.14(a)
the Center for Biological Diversity, Klamath-Siskiyou Wildlands Center, and Noah Greenwald, to list the Siskiyou Mountains salamander ( Plethodon stormi ) as a threatened or endangered species on behalf of themselves and five other organizations. The petition clearly identified itself as such and included the requisite identification information for the petitioners, as required in 50 CFR 424.14(a). In their petition, the petitioners assert that there are three separate distinct population segments (DPSs) of the Siskiyou Mountains salamander, one of which consists of the Scott Bar salamander. Alternatively, the petitioners assert that the Scott Bar salamander is a separate species and request that it be considered independently for listing. Since the time the petition was submitted, the Scott Bar salamander ( Plethodon asupak ) has been recognized as a species separate from the Siskiyou Mountains salamander (Mead et al. 2005, pp. 169-171), and we have reviewed it separately in making this finding. The petitioners also requested the Service to consider whether the Siskiyou Mountains salamander (and therefore the Scott Bar salamander, as well) warrants listing throughout a significant portion of its range, and requested designation of critical habitat for both species concurrent with their listing. In a July 19, 2004, letter to the petitioners, we responded that we reviewed the petition for both species and determined that an emergency listing was not warranted, and that because of inadequate funds for listing and critical habitat designation, we would not be able to otherwise address the petition to list the Siskiyou Mountains salamander and Scott Bar salamander at that time.
On June 23, 2005, we received a 60-day notice of intent to sue and on August 23, 2005, the Center for Biological Diversity and four other groups filed a Complaint for Declaratory and Injunctive Relief in Federal District Court for the District of Oregon ( Center for Biological Diversity et al. v. Norton et al. , No
to list the Siskiyou Mountains salamander and Scott Bar salamander at that time.
On June 23, 2005, we received a 60-day notice of intent to sue and on August 23, 2005, the Center for Biological Diversity and four other groups filed a Complaint for Declaratory and Injunctive Relief in Federal District Court for the District of Oregon ( Center for Biological Diversity et al. v. Norton et al. , No. 3:05-CV-1311-BR), challenging our failure to issue a 90-day finding on the petition to list the Siskiyou Mountains salamander and Scott Bar salamander. On December 28, 2005, we reached an agreement with the plaintiffs to complete the 90-day finding by April 15, 2006, and if we determined that the petition presented substantial information that listing may be warranted, to complete the 12-month finding by January 15, 2007.
On April 17, 2006, the Service made its 90-day finding (71 FR 23886, April 25, 2006), concluding that the petition did not present substantial scientific or commercial information to indicate that listing the Siskiyou Mountains salamander and Scott Bar salamander may be warranted.
On July 6, 2006, the Center for Biological Diversity and others filed suit in the United States District Court for the Northern District of California ( Center for Biological Diversity et al. v. Dirk Kempthorne et al. , No. C-06-4186-WHA), challenging the merits of that finding. On January 19, 2007, the District Court determined the 90-day finding was arbitrary and capricious, vacated and remanded the finding, and ordered the Service to make a new finding by March 23, 2007.
A new 90-day finding was signed on March 22, 2007, and we published it in the Federal Register on March 29, 2007 (72 FR 14750)
rne et al. , No. C-06-4186-WHA), challenging the merits of that finding. On January 19, 2007, the District Court determined the 90-day finding was arbitrary and capricious, vacated and remanded the finding, and ordered the Service to make a new finding by March 23, 2007.
A new 90-day finding was signed on March 22, 2007, and we published it in the Federal Register on March 29, 2007 (72 FR 14750). In that 90-day finding, we concluded that the petition presented substantial scientific or commercial information to indicate that listing the Siskiyou Mountains salamander and Scott Bar salamander may be warranted, announced the initiation of a status review of these taxa, and solicited comments and information to be provided in connection with the status review by May 29, 2007. This notice constitutes our 12-month finding regarding the petition to list these two species.
To ensure that this finding is based on the latest information and incorporates the opinions of the scientific community, the Service entered into a
Foreseeable Future
The principal difference between an “endangered” and a “threatened” species under the Act is whether the species is currently in danger of extinction, or if it is likely to become so “within the foreseeable future.” The Act does not define the term foreseeable future; however, we consider the foreseeable future to be affected by the biological and demographic characteristics of the species, as well as our ability to predict or extrapolate the effects of threats facing the species in the future. Quantification of the time period corresponding to the forseeable future is challenging because it necessitates making predictions about inherently dynamic political, legal, and social mechanisms that influence the degree and immediacy of potential threats to the species
istics of the species, as well as our ability to predict or extrapolate the effects of threats facing the species in the future. Quantification of the time period corresponding to the forseeable future is challenging because it necessitates making predictions about inherently dynamic political, legal, and social mechanisms that influence the degree and immediacy of potential threats to the species.
Population dynamics of the Siskiyou Mountains salamander and Scott Bar salamander are poorly known, and we are unaware of data sufficient to support estimates of longevity, generation times, or recruitment rates for these species. For example, Nussbaum et al. (1983, p. 103) state that both sexes “are thought to” mature at 5 to 6 years of age, but provide no basis for this estimate. Likewise, estimates of population and genetically effective population (N e ) size are unavailable for these species (DeGross and Bury 2007, p. 9). Because the demographic and biological characteristics of these species are so poorly understood, we must base our estimate of foreseeable future on our ability to predict or extrapolate the effects of the future threats facing these species.
Our ability to predict the effects of future threats is limited to our knowledge of the time frame of the threats potentially facing the species (e.g., timber harvest, wildfire, roads and road construction, mining and rock quarrying, disease, stochastic events, and climate change) and of any conservation activities taking place to address these threats. For example, the rate of timber harvest has declined on Federal lands (which constitute over 85 percent of the combined ranges of both species) during the last 30 years (USDA and USDI 1994, 2005) and we have no information that would lead us to predict a dramatic increase in the rate and intensity of timber harvest such that large areas of habitat will be affected to such a great degree that these species will suffer adverse impacts
est has declined on Federal lands (which constitute over 85 percent of the combined ranges of both species) during the last 30 years (USDA and USDI 1994, 2005) and we have no information that would lead us to predict a dramatic increase in the rate and intensity of timber harvest such that large areas of habitat will be affected to such a great degree that these species will suffer adverse impacts. In the event that the rate and intensity of timber harvesting were to increase dramatically, it would take some period of time (depending on the actual increase of the rate and intensity, and the impact of the harvesting at issue on the salamanders) for the cumulative impact of the timber harvesting to have a significant effect on the species. Because the available evidence suggests that the salamanders recover for even intensive disturbances such as clearcutting (from 11 years (Bull et al. 2006, p. 21) to 30 years (Welsh et al. 2007b) for Siskiyou Mountains salamanders), the species would only become in danger of extinction if that increased level and intensity of harvest lasted long enough to effect sufficient habitat at nearly the same time such that it overcame the apparent resiliency of the species to such disturbances. Further, while scientists predict that the rate of temperature change will continue to increase throughout the present century (EPRI 2003, p. 3; Hayhoe et al. 2004, p. 12423; Cayan et al. 2006, pp. 11-14, 31; Maurer 2007, p. 317), the effects of climate change on these species are uncertain and estimation of the timing of potential effects would be speculative.
We do not have sufficient demographic information on Siskiyou Mountains salamanders or Scott Bar salamanders, nor on the trajectory of potential threats when combined with existing regulatory mechanisms, on which to base a precise definition of foreseeable future
, the effects of climate change on these species are uncertain and estimation of the timing of potential effects would be speculative.
We do not have sufficient demographic information on Siskiyou Mountains salamanders or Scott Bar salamanders, nor on the trajectory of potential threats when combined with existing regulatory mechanisms, on which to base a precise definition of foreseeable future. Given the stability of Federal Land and Resource Management Plans and the Northwest Forest Plan (NWFP) since its establishment in 1994, we assume that significant changes to current land management practices on Federal lands are not likely to occur within 20 years. We note that the changes in Federal land management that we can anticipate may happen in the short term, including termination of the Survey and Manage Program and Western Oregon Plan Revision, discussed below, are unlikely to result in the sort of significant changes that might have an important effect on the conservation status of the species. If a significant change were to occur, we estimate that, because of logistical and regulatory limitations imposed on the rate of planning and implementing significant land management actions, actual management activities could take an additional 20 years to reach a magnitude of effect that would measurably affect salamander populations. Therefore, we conclude that the foreseeable future for the salamanders does not extend beyond 40 years. In other words, we have sufficient confidence in our estimates of the threats and reaction of the two species to those threats to draw a conclusion as to the likelihood of endangerment over only at most 40 years. Beyond that period, our level of confidence is such that any conclusions we drew would be too speculative on which to base current action
the salamanders does not extend beyond 40 years. In other words, we have sufficient confidence in our estimates of the threats and reaction of the two species to those threats to draw a conclusion as to the likelihood of endangerment over only at most 40 years. Beyond that period, our level of confidence is such that any conclusions we drew would be too speculative on which to base current action. We find that this estimate of the foreseeable future is both reasonable and appropriate because it focuses this status review on the time frame in which current social and political change may affect species management, which we consider to have the most likely potential for meaningful near-term influence on the status of these species.
Species Descriptions
Like others in the Family Plethodontidae (the lungless salamanders), the Siskiyou Mountains salamander and Scott Bar salamander are completely terrestrial, medium-sized, slender-bodied salamanders with short limbs and a dorsal stripe. Both species are found in or near talus (loose surface rock) and fissured rock outcrops where moisture and humidity are high enough to allow respiration through their skin (Feder 1983, p. 296; Nussbaum et al. 1983, pp. 73, 90, and 102; Stebbins 2003, p. 168). Both species are endemic to the Klamath-Siskiyou Mountains of southern Oregon and northern California, where they are considered as part of a species complex that includes and is named for the similar Del Norte salamander ( Plethodon elongatus ).
Members of the Plethodon elongatus Complex differ physically from other regional members of the genus Plethodon. Species in the Plethodon elongatus Complex have webbed toes, while Dunn's salamander ( P. dunni ) and western red-backed salamander ( P. vehiculum ) do not (Highton 1962, pp. 255-256)
cies complex that includes and is named for the similar Del Norte salamander ( Plethodon elongatus ).
Members of the Plethodon elongatus Complex differ physically from other regional members of the genus Plethodon. Species in the Plethodon elongatus Complex have webbed toes, while Dunn's salamander ( P. dunni ) and western red-backed salamander ( P. vehiculum ) do not (Highton 1962, pp. 255-256). The larger number of trunk vertebrae and costal grooves (vertical creases along the side of the body), as well as the smaller number of vomerine teeth (teeth on the vomer bone in the roof of the mouth) further distinguish the Plethodon elongatus Complex from the rest of the western Plethodon species (Highton and Brame 1965, p. 1; Brodie 1970, pp. 503-505; Nussbaum et al. 1983, p. 102; Mead et al. 2005, pp. 163-166).
The Siskiyou Mountains salamander was described in 1965, two years after it was first identified (Highton and Brame 1965, p. 1). It is characterized by a modal number of 17 costal grooves and 4 to 5.5 intercostal folds (folds of skin between the costal grooves) between the toes of adpressed limbs (limbs firmly pressed against the sides of the body) (Nussbaum et al. 1983, p. 102; Leonard et al. 1993, p. 78). Adults have a light- to purplish-brown dorsum, and the body is sprinkled with a moderate to dense array of white to yellow flecks, concentrated on the sides and limbs and away from the light-brown dorsal stripe (Highton and Brame 1965, p. 1; Nussbaum et al. 1983, p. 102). Juveniles are black and have an olive-tan dorsal stripe that extends onto the tail.
The Scott Bar salamander is more robust and has a wider head and longer limbs than the Del Norte salamander and Siskiyou Mountains salamander. It has fewer intercostal folds between adpressed limbs (2.5 to 3.5) than either the Del Norte salamander (5 to 6) or Siskiyou Mountains salamander (4 to 5.5), and the modal number of costal grooves (17) is one less than in the Del Norte salamander (18)
l.
The Scott Bar salamander is more robust and has a wider head and longer limbs than the Del Norte salamander and Siskiyou Mountains salamander. It has fewer intercostal folds between adpressed limbs (2.5 to 3.5) than either the Del Norte salamander (5 to 6) or Siskiyou Mountains salamander (4 to 5.5), and the modal number of costal grooves (17) is one less than in the Del Norte salamander (18). The Scott Bar salamander has a longer body relative to its tail length and longer forelimbs and hindlimbs than the Siskiyou Mountains salamander or Del Norte salamander. The coloration of the Scott Bar salamander is similar to that of the Siskiyou Mountains salamander and is described in Mead et al. (2005, p. 170). Despite the morphological differences described in Mead et al. (2005, pp. 169-171), the two species are difficult to distinguish in the field.
Taxonomy
The Siskiyou Mountains salamander was first identified in 1963, adding the second form to what is now referred to as the Plethodon elongatus Complex (Highton and Brame 1965, p. 1). Early distinctions between Siskiyou Mountains salamanders and Del Norte salamanders were based on morphological traits and coloration (Highton and Brame 1965, p. 1; Brodie 1970, pp. 503-505; Bury 1973, p. 57). However, it is now clear that field identification of these species based on coloration is unreliable because both species exhibit geographic variation in coloration (Brodie 1970, p. 503; Bury 1999, pp. 9-10).
Researchers have cited morphological differences as evidence of a taxonomic distinction between Siskiyou Mountains salamanders and Del Norte salamanders. Perhaps the most convincing support for distinguishing between these forms was provided by Mead et al. (2005, pp. 165-166), who found that all three species in the Plethodon elongatus Complex differed in average measurements of male snout-vent length, forelimb length, and head width; and female snout-vent length, forelimb length, and internarial distance
ains salamanders and Del Norte salamanders. Perhaps the most convincing support for distinguishing between these forms was provided by Mead et al. (2005, pp. 165-166), who found that all three species in the Plethodon elongatus Complex differed in average measurements of male snout-vent length, forelimb length, and head width; and female snout-vent length, forelimb length, and internarial distance. Additionally, both Siskiyou Mountains salamanders and Scott Bar salamanders have a smaller modal number of costal folds and proportionally larger forelimbs than Del Norte salamanders, contributing to their more robust appearance (Highton and Brame 1965, p. 1; Mead et al. 2005, p. 170).
Phylogenetic studies of the Plethodon elongatus Complex have provided further support for classifying Siskiyou Mountains salamanders and Del Norte salamanders as closely related species (Mahoney 2001, p. 183; Mahoney 2004, pp. 155-161; Bury and Welsh 2005, p. 842; Mead et al. 2005, p. 166). Phylogenetic studies of these species have also shown that early studies of the morphology of Del Norte salamanders along the Klamath River between Happy Camp and Seiad Valley, California, were in fact describing Siskiyou Mountains salamanders (Pfrender and Titus 2001, p. 15; DeGross 2004, pp. 17-18; Mahoney 2004, p. 5; Mead et al. 2005, p. 173; Mead 2006, pp. 15-16). In fact, Bury (1973, p. 57) proposed possible intergradation between these two species, and Stebbins (1985, p. 47; 2003, pp. 173-174) demoted the Siskiyou Mountains salamander to a subspecies of Del Norte salamander. However, recent research suggests that little gene flow occurs between these species across their zone of contact in the Indian Creek drainage in western Siskiyou County, California (DeGross 2004, p. 40; DeGross et al. unpublished)
tergradation between these two species, and Stebbins (1985, p. 47; 2003, pp. 173-174) demoted the Siskiyou Mountains salamander to a subspecies of Del Norte salamander. However, recent research suggests that little gene flow occurs between these species across their zone of contact in the Indian Creek drainage in western Siskiyou County, California (DeGross 2004, p. 40; DeGross et al. unpublished).
Phylogenetic studies of the Siskiyou Mountains salamander have indicated that this species consists of two distinct genetic lineages: North Clade (populations within the Applegate River drainage and on the crest of the Siskiyou Mountain Range) and South Clade (populations south of the Siskiyou Mountain Range crest and adjacent to the Klamath River) (Pfrender and Titus 2001, pp. 5-6; DeGross 2004, pp. 24-44; Mahoney 2004, p. 8; Mead et al. 2005, pp. 163-166). A third, more divergent, group was also identified and is now recognized as a separate species, the Scott Bar salamander.
Based on levels of genetic divergence between species in the Plethodon elongatus Complex, researchers estimated that the Del Norte salamander and Siskiyou Mountains salamander lineages diverged approximately 4 million years ago and that their shared ancestral lineage diverged from that of the Scott Bar salamander between 20 and 26 million years ago (Mahoney 2004, p. 15; Mead et al. 2005, p. 165). Therefore, the Scott Bar salamander lineage appears to be the basal (most primitive, from which others are derived) lineage of the Plethodon elongatus Complex. Given the time periods during which these species diverged, speciation within this complex was probably influenced by Pleistocene glaciation (Soltis et al. 1997, pp. 369-370; Bury 1999, p. 22; DeGross and Bury unpublished).
Differences between Scott Bar salamanders and the other members of the Plethodon elongatus Complex are not limited to their genetic divergence. As noted above, Mead et al. (2005, pp. 165-166) found differences in morphological measurements of all three species
plex was probably influenced by Pleistocene glaciation (Soltis et al. 1997, pp. 369-370; Bury 1999, p. 22; DeGross and Bury unpublished).
Differences between Scott Bar salamanders and the other members of the Plethodon elongatus Complex are not limited to their genetic divergence. As noted above, Mead et al. (2005, pp. 165-166) found differences in morphological measurements of all three species. Nonetheless, questions about the validity of the current classification of these species persist (sensu Wake and Jockusch 2000, p. 117). Further, the ranges of the Scott Bar salamander and Siskiyou Mountains salamander abut each other north of the Klamath River and south of Horse Creek, so it is possible that these species interbreed in this area. Measurements of gene flow between these species would be helpful to further clarify the taxonomy of southern populations of Siskiyou Mountains salamanders and Scott Bar salamanders and define the interspecific boundaries for each species range (DeGross and Bury 2007, p. 4; Wake and Jockusch 2000, p. 117).
The Service recognizes that questions about the taxonomy of the Plethodon elongatus Complex remain and that research on this topic is ongoing. However, for the purpose of this finding, we evaluated the threats to the Siskiyou Mountains salamander and Scott Bar salamander separately because the preponderance of available evidence currently supports recognition of these forms as separate species. Even so, the ecological research on these species was
For the purposes of this finding, we use the following hierarchy of taxonomic names:
(1) Plethodon elongatus Complex: Plethodon salamanders within the geographic region occupied by Del Norte salamander, Siskiyou Mountains salamander, and Scott Bar salamander.
(2) Siskiyou Mountains salamander Complex: The three known genetic entities previously classified as Siskiyou Mountains salamander, consisting of the Scott Bar salamander, Siskiyou Mountains salamander North Clade, and Siskiyou Mountains salamander South Clade.
don salamanders within the geographic region occupied by Del Norte salamander, Siskiyou Mountains salamander, and Scott Bar salamander.
(2) Siskiyou Mountains salamander Complex: The three known genetic entities previously classified as Siskiyou Mountains salamander, consisting of the Scott Bar salamander, Siskiyou Mountains salamander North Clade, and Siskiyou Mountains salamander South Clade.
(3) Siskiyou Mountains salamander (North and South Clades combined), not including the Scott Bar salamander.
(4) Individual genetic subunits of Siskiyou Mountains salamander: North Clade (hereafter referred to as the Applegate salamander) and South Clade (hereafter referred to as the Grider salamander).
Biology
Like other members of the Family Plethodontidae, Siskiyou Mountains and Scott Bar salamanders require contact with moisture for respiration through their permeable skin (Feder 1983, pp. 292-293). Desiccation is lethal to Plethodon species and therefore, surface activity by Siskiyou Mountains and Scott Bar salamanders primarily occurs at night, when the air is cool and moist (Nussbaum 1974, p. 3; Nussbaum et al. 1983, p. 103; Clayton and Nauman 2005, p. 139; Mead et al. 2005, p. 118). Peak periods of surface activity occur during the rainy season (usually late fall and spring) (Clayton and Nauman 2005, p. 139; Mead et al. 2005, p. 118). These salamanders retreat to underground refugia during the extreme climatic conditions common during summer and winter in the eastern Klamath Mountains (Nussbaum 1974, p. 3). They may forage at the surface during the summer (Nussbaum et al. 1983, p. 103) but probably only in sites with relatively cool, moist microclimates. Little is known about these species' behavior, but many researchers assume that they are inactive underground and that foraging and reproduction only occur during brief periods of surface activity (Feder 1983, p. 305). However, it is possible that these activities also occur below the surface (Welsh and Lind 1992, p. 433)
. 103) but probably only in sites with relatively cool, moist microclimates. Little is known about these species' behavior, but many researchers assume that they are inactive underground and that foraging and reproduction only occur during brief periods of surface activity (Feder 1983, p. 305). However, it is possible that these activities also occur below the surface (Welsh and Lind 1992, p. 433). The limited surface activity by these species is reflected in survey protocols for Siskiyou Mountains salamanders, which require that surveys be restricted to periods of relative humidity above 65 percent, air temperatures between 39.2 and 68 °F (4 to 20 °C), soil temperatures between 38.3 and 64.4 °F (3.5 to 18 °C), and moist soil conditions (Clayton et al. 1999, p. 133).
Plethodon salamanders are fully terrestrial amphibians and do not need standing or flowing water for any stage of their life cycle (Zug et al. 2001, p. 383). Eggs are thought to be laid in small clusters deep in moist, rocky substrates, but this has not been observed by researchers. Females have clutches of 2 to 18 eggs, with an average of 9 eggs per clutch (Nussbaum et al. 1983, pp. 21-23). Juveniles emerge in late fall and early spring. Welsh and Lind (1992, p. 432) reported that juveniles captured in mid-spring were significantly larger than would be expected if newly hatched. These salamanders appear to become reproductively mature at 5 to 6 years and are relatively long-lived (up to 15 years) (Nussbaum et al. 1983, p. 103; Clayton and Nauman 2005, p. 139). Females appear to breed every other year (Nussbaum 1974, p. 22).
Siskiyou Mountains and Scott Bar salamanders are `lie-and-wait' predators that prey on a variety of small terrestrial invertebrates, including spiders, pseudoscorpions, mites, ants, collembolans, and beetles (Nussbaum et al. 1983, p. 103). Seasonal changes in diet have been reported for these species (Nussbaum 1974, p. 24)
p. 139). Females appear to breed every other year (Nussbaum 1974, p. 22).
Siskiyou Mountains and Scott Bar salamanders are `lie-and-wait' predators that prey on a variety of small terrestrial invertebrates, including spiders, pseudoscorpions, mites, ants, collembolans, and beetles (Nussbaum et al. 1983, p. 103). Seasonal changes in diet have been reported for these species (Nussbaum 1974, p. 24). Predators of these species have not been identified but may include snakes, shrews, or animals that opportunistically forage in spring leaf litter and debris (e.g., ground-foraging birds). Several researchers have hypothesized that interspecific and intraspecific competition are important factors in the population ecology of Siskiyou Mountains and Scott Bar salamanders (Nishikawa 1985, p. 1290; Mathis 1989, p. 790; Griffis and Jaeger 1998, p. 2500). These species' ranges overlap with those of ensatina ( E. eschscholtzii oregonensis ) and black salamanders ( Aneides flavipunctatus ), and a recent study described one site where they are sympatric with Del Norte salamanders (Mead 2006, p. 8). We are not aware of any information about parasites or diseases affecting these species or information about symbiotic or mutualistic interactions with other organisms.
Habitat Associations
Siskiyou Mountains salamanders and Scott Bar salamanders occur on slopes with rocky soils or talus (loose surface rock) outcrops. These substrates provide interstitial spaces into which these animals can retreat from the climatic extremes of the eastern Klamath Mountains. These salamanders are occasionally found under other types of cover, such as bark, limbs, or logs, but only during wet weather when moisture is high and only in close proximity to suitable rocky substrates (Nussbaum 1974, p. 13; Nussbaum et al. 1983, p. 102). Like other plethodontids, Siskiyou Mountains salamanders and Scott Bar salamanders require contact with moisture for respiration through their skin
alamanders are occasionally found under other types of cover, such as bark, limbs, or logs, but only during wet weather when moisture is high and only in close proximity to suitable rocky substrates (Nussbaum 1974, p. 13; Nussbaum et al. 1983, p. 102). Like other plethodontids, Siskiyou Mountains salamanders and Scott Bar salamanders require contact with moisture for respiration through their skin. Therefore, habitat characteristics that influence forest microclimates, especially relative humidity and soil surface moisture, are likely important to these species. Based on these species' similar natural histories and physiologies (see “Biology” section), occurrence in the same region, and previous designation as one species, we assume that Siskiyou Mountains salamanders and Scott Bar salamanders have similar habitat requirements. As noted above, nearly all of the available information on these species comes from studies conducted on both species, prior to recognition of Scott Bar salamander as a separate species.
Early observational studies of Siskiyou Mountains salamanders found that these animals are highly associated with talus and other rocky substrates (Highton and Brame 1965, p. 1; Storm 1966, p. 1; Nussbaum 1974, p. 13; Clayton and Nauman 2005, p. 139; Mead et al. 2005, p. 118). Nussbaum (1974, p. 13) found that the densest populations were on heavily wooded, north-facing slopes that also had talus deposits or fissured rock outcrops. Many of the earliest known populations of Siskiyou Mountains salamanders occurred in talus road cuts, where the underlying rock substrate was exposed and detection of salamanders was facilitated (Nussbaum 1974, p. 13).
The degree to which Siskiyou Mountains salamanders and Scott Bar salamanders are associated with late-seral forest conditions has been the subject of considerable uncertainty and debate among scientists and land managers. Understanding this debate is essential to understanding the Service's finding for these species
was exposed and detection of salamanders was facilitated (Nussbaum 1974, p. 13).
The degree to which Siskiyou Mountains salamanders and Scott Bar salamanders are associated with late-seral forest conditions has been the subject of considerable uncertainty and debate among scientists and land managers. Understanding this debate is essential to understanding the Service's finding for these species. The debate is exemplified by the salamander population at Muck-a-Muck Creek, the type locality from which the Scott Bar salamander was described (Mead et al. 2005, p. 169). Biologists and researchers
The results of studies of habitat relationships conducted to date are equivocal or provide limited inferences. Limited inferences result from either (1) lack of a random or systematic sampling design that allows inference to a larger population, or (2) single-visit sampling that fails to incorporate the low and variable detection rates associated with these species. Two analyses of a single, relatively large-scale, single-visit, random, sampling-based study suggested an association with closed-canopy, older forest (Ollivier et al. 2001; Welsh et al. 2007a), whereas field studies evaluating habitat attributes at known (not randomly or systematically selected) locations demonstrated that the species are found in a wide range of forest structural conditions (Farber et al. 2001; Bull et al. 2006; Farber 2007a). We are not aware of any rigorous studies evaluating the species' demographic responses to forest conditions.
The most rigorous research of these species' habitat associations was conducted by Ollivier et al. (2001) and Welsh et al. (2007a). These studies used the same data set and somewhat different analytical techniques. The data used in both analyses were collected at 61 sites occupied by Siskiyou Mountains salamanders and possibly Scott Bar salamanders (a few sites were located within the range of what were later recognized as Scott Bar salamanders)
tat associations was conducted by Ollivier et al. (2001) and Welsh et al. (2007a). These studies used the same data set and somewhat different analytical techniques. The data used in both analyses were collected at 61 sites occupied by Siskiyou Mountains salamanders and possibly Scott Bar salamanders (a few sites were located within the range of what were later recognized as Scott Bar salamanders). These sites were compared with sites classified as unoccupied by salamanders (see below). These studies found that salamander populations on either side of the Siskiyou Crest appeared to occupy habitat based on different environmental factors (Welsh et al. 2007a, p. 28). The authors primarily attributed this result to geographic differences in precipitation, illumination (topographic variation in sunlight or shading), and vegetation (Welsh et al. 2007a, pp. 19, and 28). Based on these differences, they suggested that suitable habitat is less abundant and more patchily distributed on the south side of the crest than on the north side (Welsh et al. 2007a, p. 28). Although these results differed somewhat for salamanders on either side of the Siskiyou Crest, they generally indicated that sites occupied by salamanders contained attributes that likely moderate surface microclimates for these animals (e.g., greater canopy closure, more leaf litter cover, more decaying logs) or that are associated with moist, cool microclimates (e.g., less grass cover, more sword fern cover) (Ollivier et al. 2001, pp. 17-21, 26-29; Welsh et al. 2007a, pp. 24, 27). Both analyses concluded that Siskiyou Mountains (and possibly Scott Bar) salamanders are “a mature to old-growth-forest-associated species that exists at its biological optimum under conditions found primarily in later seral stages of mixed conifer-hardwood forests in northwestern California and southwestern Oregon” (Ollivier et al. 2001, p. 42; Welsh et al. 2007a, p. 31)
t al. 2007a, pp. 24, 27). Both analyses concluded that Siskiyou Mountains (and possibly Scott Bar) salamanders are “a mature to old-growth-forest-associated species that exists at its biological optimum under conditions found primarily in later seral stages of mixed conifer-hardwood forests in northwestern California and southwestern Oregon” (Ollivier et al. 2001, p. 42; Welsh et al. 2007a, p. 31). However, the authors also state that “[t]oday, information on the habitat requirements of this species is incomplete and conflicting” (Welsh et al. 2007a, p. 16) and “[m]any of the biotic and abiotic requirements necessary for long-term viability for the Siskiyou Mountains salamander remain undetermined” (Welsh et al. 2007a, p. 31). It is important to note that the results of these studies only indicate correlations between forest attributes and the presence of salamanders; they do not actually demonstrate that these species select habitat based on older-forest characteristics (Welsh et al. 2007a, p. 31). For example, these salamanders may select habitat based on other factors (e.g., suitable microclimates) that often occur within older forests but that can also occur in other areas such as deep drainages and north-facing slopes.
Our understanding of the habitat associations of Siskiyou Mountains salamander and their degree of ecological dependence on specific habitat conditions is hampered by the difficulty in detecting this species during surveys. Their brief, intermittent periods of surface activity, nocturnal habits, and secretive behavior make detection of Siskiyou Mountains salamanders and Scott Bar salamanders difficult (Nussbaum 1974, p. 3; Olson et al. 2007, pp. 7-8). Welsh et al. (2007a, p. 25) estimated that their detection rates for these species were 20 and 28 percent on the south and north slopes of the Siskiyou Crest, respectively. Detection rates for other Plethodon species are similarly low: 15 percent (Bailey et al. 2004, p. 21) and 2 to 32 percent (Taub 1961, p. 695)
nd Scott Bar salamanders difficult (Nussbaum 1974, p. 3; Olson et al. 2007, pp. 7-8). Welsh et al. (2007a, p. 25) estimated that their detection rates for these species were 20 and 28 percent on the south and north slopes of the Siskiyou Crest, respectively. Detection rates for other Plethodon species are similarly low: 15 percent (Bailey et al. 2004, p. 21) and 2 to 32 percent (Taub 1961, p. 695). Because detection rates are low for these species, repeated surveys and estimation of the probability of false negatives during surveys are required to minimize or account for the probability of classifying occupied sites as unoccupied. The survey protocol developed for the NWFP Survey and Manage Guidelines (Clayton et al. 1999, p. 141) requires three survey visits to determine presence or absence of Siskiyou Mountains salamanders. Classifying occupied sites as unoccupied, or failing to account for the probability of doing so, can bias conclusions about relationships between salamanders and habitat characteristics. The presence or absence data analyzed by Ollivier et al. (2001) and Welsh et al. (2007a) were collected with a single-visit protocol, so these studies cannot reliably infer absence at sites where detections were not obtained. In fact, the California Department of Fish and Game (CDFG) used a more intensive survey protocol to resurvey 13 clear-cut or precanopy (0 to 30 years-old) sites classified as unoccupied by Ollivier et al. (2001) and Welsh et al. (2007a) and found Siskiyou Mountains salamanders at 5 sites, Scott Bar salamanders at 2 sites, and Del Norte salamanders at 1 site (Bull et al. 2006, p. 25). While this finding does not appear to change the general conclusion described by Ollivier et al. (2001) and Welsh et al. (2007a) that salamanders were more likely to be detected in closed-canopied older forest than in more open sites, it acts to substantially weaken the inference of Ollivier et al. (2001, p. 42) and Welsh et al. (2007a, p
Del Norte salamanders at 1 site (Bull et al. 2006, p. 25). While this finding does not appear to change the general conclusion described by Ollivier et al. (2001) and Welsh et al. (2007a) that salamanders were more likely to be detected in closed-canopied older forest than in more open sites, it acts to substantially weaken the inference of Ollivier et al. (2001, p. 42) and Welsh et al. (2007a, p. 31), that these species are ecologically dependent on conditions primarily found in mature or late-seral stage forests.
Two other studies have examined potential relationships between habitat attributes and abundances of Siskiyou Mountains salamanders and Scott Bar salamanders. Farber (2007a) described sites occupied by Scott Bar salamanders on private timber company property and adjacent National Forest land. This study compared salamander abundances and habitat characteristics at 26 sites
To support their argument that the Siskiyou Mountains salamander is critically imperiled by habitat loss, the petitioners rely heavily on statements made by Welsh et al. (2007a) as providing new scientific information that the salamanders are highly associated with, and ecologically dependent on, old-growth forest conditions, and the petitioners highlight an ongoing debate between Dr. Welsh and the CDFG (Greenwald and Curry 2007, pp. 4-7). As discussed above, we conclude that the survey methodology employed by Ollivier et al. (2001) and Welsh et al. (2007a, p. 18) was inadequate to rigorously determine salamander absence as required for the presence-absence statistical modeling method used to analyze the data. The single-visit sampling methodology these authors employed is more appropriate for comparisons of relative abundance among habitat types, which is how we interpreted their results. The fact that salamanders were subsequently detected by CDFG at over half of the `absent' sites analyzed by Welsh et al
bsence as required for the presence-absence statistical modeling method used to analyze the data. The single-visit sampling methodology these authors employed is more appropriate for comparisons of relative abundance among habitat types, which is how we interpreted their results. The fact that salamanders were subsequently detected by CDFG at over half of the `absent' sites analyzed by Welsh et al. (2007a) does not negate the importance of this study or the habitat associations it describes; it does, however, limit the strength of inference regarding the degree to which Siskiyou Mountains salamanders may require old-growth forest conditions. We do not consider the field studies conducted by CDFG (Bull et al. 2006) as providing competing scientific research requiring reconciliation with the statistical design of the Welsh et al. (2007a) study. The CDFG field studies do, however, provide habitat results from a large sample of occupied salamander locations, which, in combination with similar data sets from Farber et al. (2001), constitute a significant source of information on these species.
A model was recently developed for predicting the occurrence of Siskiyou Mountains salamanders north of the Siskiyou Crest (Reilly et al. 2007). This model incorporated three variables reported by Ollivier et al. (2001) and Welsh et al. (2007a) to be positively related to occupancy by Siskiyou Mountains salamanders: rocky soil types, forest canopy closures above 70 percent, and conifer forest with average tree sizes greater than 17 inches (43 centimeters) in diameter at breast height (DBH) (Reilly et al. 2007, p. 1). An additional variable modeling topographical variation in sunlight or shading was also incorporated (Reilly et al. 2007, p. 2). Strategic surveys of sites that were predicted by the model to be occupied had 65 percent detection rates (34 of 52 sites were occupied), the highest ever reported for this species (Nauman and Olson 2004, p. 3)
diameter at breast height (DBH) (Reilly et al. 2007, p. 1). An additional variable modeling topographical variation in sunlight or shading was also incorporated (Reilly et al. 2007, p. 2). Strategic surveys of sites that were predicted by the model to be occupied had 65 percent detection rates (34 of 52 sites were occupied), the highest ever reported for this species (Nauman and Olson 2004, p. 3). In addition to indicating the usefulness of presence or absence modeling as a scientific and management tool, this relatively high detection rate seems to support the associations described by Ollivier et al. (2001) and Welsh et al. (2007a).
Summary of Habitat Associations
Few studies of the habitat associations of Siskiyou Mountains salamanders and Scott Bar salamanders have been conducted. These include only a single large, systematic sample effort, from which two analyses were conducted (Ollivier et al. 2001 and Welsh et al. 2007a). These analyses found positive relationships between detection of Siskiyou Mountains salamanders (and possibly Scott Bar salamanders) and habitat characteristics that likely moderate surface microclimates for them (e.g., high canopy closure, more leaf litter cover, more decaying logs). Studies by Farber et al. (2001), Farber (2007a), and CDFG (Bull et al. 2006) were smaller and less rigorous than the analyses by Ollivier et al. (2001) and Welsh et al. (2007a). However, they clearly showed that Siskiyou Mountains salamanders and Scott Bar salamanders occur within a wide range of habitat conditions, including clear-cuts and young forest. The limited available evidence suggests that these species are highly associated with talus and fissured rock outcrops and are generally associated with moist, cool surface microclimates. These salamanders are likely more common in mature and old-growth forest than in other forest classes, but many salamander sites occur in other habitat types
tat conditions, including clear-cuts and young forest. The limited available evidence suggests that these species are highly associated with talus and fissured rock outcrops and are generally associated with moist, cool surface microclimates. These salamanders are likely more common in mature and old-growth forest than in other forest classes, but many salamander sites occur in other habitat types. Potential differences in the size and viability of populations in open or disturbed habitat and mature or old-growth habitat are discussed below under Factor A.
Range and Extant Distribution
Range
Currently known populations within the Siskiyou Mountains salamander Complex occur within Jackson County and the extreme southeast portion of Josephine County in southwestern Oregon, and in northern Siskiyou County in northwestern California. In Oregon, known populations occur in the Applegate Valley watershed north of the Siskiyou Crest. In California, the species complex occurs in the Klamath River drainage, south of the Siskiyou Crest, in the area bounded to the west by Indian Creek and the headwaters of Grider Creek, Kelsey Creek, and Canyon Creek; to the south by Scott Bar Mountain; and to the east by the headwaters of Mill Creek and the Horse Creek drainage. This range is subdivided into three areas based on genetically distinct populations. Siskiyou Mountains salamander North Clade (or Applegate Population) occupies the area north of the Siskiyou Crest; Siskiyou Mountains salamander South Clade (or Grider Population) occurs south of the Siskiyou Crest; and the Scott Bar salamander is found in the southeastern portion of the former range of Siskiyou Mountain salamander South Clade.
Boundary lines for the ranges of the members of the Siskiyou Mountains salamander Complex have been variously estimated by several authors (DeGross 2004, p. 15; Nauman and Olson 2004, p. 2; 2007, p. 4) and have changed through time as additional populations were discovered and results of genetic analyses were obtained
stern portion of the former range of Siskiyou Mountain salamander South Clade.
Boundary lines for the ranges of the members of the Siskiyou Mountains salamander Complex have been variously estimated by several authors (DeGross 2004, p. 15; Nauman and Olson 2004, p. 2; 2007, p. 4) and have changed through time as additional populations were discovered and results of genetic analyses were obtained. For the purposes of this finding, we delineated species' ranges and calculated landscape statistics based on
Our understanding of the range and distribution of the Siskiyou Mountains salamander Complex is dynamic; the known range has roughly tripled between 1980 and 2007, doubling between 1993 and 1998 (Olson et al. 2007, p. 20). Biologists familiar with the species believe that the currently known range is well-defined to the east by xeric conditions and unsuitable soil types, and to the west by the range of the Del Norte salamander (Olson et al. 2007, p. 19). However, it is likely that the known range will continue to be refined and expanded through discovery of additional populations to the south in the Scott River, Canyon Creek, Kelsey Creek, and Upper Grider Creek drainages, and to the north in the Applegate River drainage. For example, two detections of salamanders described as Siskiyou Mountains salamanders were reported by a Survey and Manage Guidelines survey crew near the town of Rogue River in 2006 (DeGross 2007). If confirmed, these detections would represent a range expansion of roughly 5 miles (mi) (8.45 kilometers (km)).
We were unable to find any information suggesting that the occupied range of any member of the Siskiyou Mountains salamander Complex is different from its historical range. Many occupied locations exist within watersheds that have sustained considerable physical modification by historical mining, roadbuilding, and logging
epresent a range expansion of roughly 5 miles (mi) (8.45 kilometers (km)).
We were unable to find any information suggesting that the occupied range of any member of the Siskiyou Mountains salamander Complex is different from its historical range. Many occupied locations exist within watersheds that have sustained considerable physical modification by historical mining, roadbuilding, and logging. As described above, the species' ranges appear to be defined by climatic conditions, soil and parent material type, and the adjacent Del Norte salamander (Olson et al. 2007, p. 19).
Distribution
The distribution of Siskiyou Mountains and Scott Bar salamander populations within their respective species' ranges is poorly known. With the exception of systematic surveys conducted by Ollivier et al. (2001) and Nauman and Olson (2004a and 2004b), the majority of surveys have been opportunistic or conducted in support of timber management planning activities. Large areas within the species' known ranges remain unsurveyed due to poor access or lack of planned projects requiring surveys. The lack of systematic surveys may result in biased estimates of population distribution. For example, because CDFG requires surveys for Siskiyou Mountains salamanders and Scott Bar salamanders during the Timber Harvest Plan (THP) review process, a high proportion (40 percent) of known Scott Bar salamander locations have been reported on private timberlands, which accounts for only 22 percent of the known range of the species (see Table 1 below).
Table 1.—Proportion of Land Ownership Within the Estimated Ranges of Siskiyou Mountains Salamanders (SMS) and Scott Bar Salamanders (SBS) Applegate SMS (%) Grider SMS (%) Scott Bar salamander (%) SMS-SBS complex (%) Private Lands 15 9 22 15 Federal Lands: USFS 66 91 78 76 BLM 19 0 0 9 Total Area (ac) 248,870 174,285 136,740 559,895 Total Area (ha) 100,712 70,529 55,335 226,578 Population distribution is strongly influenced by the abundance and distribution of suitable talus habitat
s Salamanders (SMS) and Scott Bar Salamanders (SBS) Applegate SMS (%) Grider SMS (%) Scott Bar salamander (%) SMS-SBS complex (%) Private Lands 15 9 22 15 Federal Lands: USFS 66 91 78 76 BLM 19 0 0 9 Total Area (ac) 248,870 174,285 136,740 559,895 Total Area (ha) 100,712 70,529 55,335 226,578 Population distribution is strongly influenced by the abundance and distribution of suitable talus habitat. Using a Geographic Information System (GIS)-based predictive model, the Survey and Manage Guidelines Species Review Panel for Siskiyou Mountains salamanders estimated that roughly 30 percent of the known range north of the Siskiyou Crest consisted of high-quality talus habitat (USDA and USDI Species Review Panel 2002), but pre-disturbance surveys conducted in the same area found that 3 to 14 percent of a given planning area (10,000 to 15,000 ac (4,047 to 6,070 ha)) consisted of suitable rock substrate (USDA and USDI Species Review Panel 2001). Based on surveys and mapping of rock habitat, Timber Products Company estimated that approximately 18 percent of their surveyed lands within the range of the Scott Bar salamander was composed of suitable talus habitat (Farber 2006). Using a similar methodology, Fruit Growers Supply Company (2007) estimated that 19 percent of 2,615 ac (1,058 ha) surveyed within the range of the Applegate Population of the Siskiyou Mountains salamander was composed of suitable talus habitat.
The Siskiyou Mountains salamander Complex occurs within a roughly 500,000 ac (202,346 ha) area dominated by Federal lands (see Table 1). The range of the Applegate Population (North Clade) of the Siskiyou Mountains salamander occurs within 248,870 ac (100,712 ha), consisting primarily (85 percent) of Federal lands, and more than 90 percent of the 174,285 ac (70,529 ha) range of the Grider Population (South Clade) of the Siskiyou Mountains salamander occurs on Federal lands (see
Known populations appear to be well-distributed across their respective species' ranges
on (North Clade) of the Siskiyou Mountains salamander occurs within 248,870 ac (100,712 ha), consisting primarily (85 percent) of Federal lands, and more than 90 percent of the 174,285 ac (70,529 ha) range of the Grider Population (South Clade) of the Siskiyou Mountains salamander occurs on Federal lands (see
Known populations appear to be well-distributed across their respective species' ranges. To evaluate spatial distribution of salamander locations within each species' range at a coarse scale, we compared known locations to watershed boundaries within each species' range. Site locations of the Applegate Population of the Siskiyou Mountains salamander occur within 19 of the 21 watersheds that constitute the range of this group. The range of the Grider Population of the Siskiyou Mountains salamander is composed of 36 watersheds of which 23 (64 percent) contain known populations. The 13 watersheds without known salamander locations are primarily situated in Wilderness and Roadless areas where access is difficult and few surveys have been conducted. Known locations of Scott Bar salamanders occupy 17 of the 25 watersheds within their range. Of the eight watersheds without known locations, six are within Wilderness and Roadless areas where suitable habitat exists but surveys have not been conducted.
Nauman and Olson (2007) conducted surveys at a stratified random sample of points located on Federal lands within the range of the Grider Population of the Siskiyou Mountains salamander and the Scott Bar salamander. They found occupancy rates (presence or absence) to be similar at high-elevation (greater than 4,000 feet (ft) (1,219 meters (m)) sites and low-elevation (less than 4,000 ft (1,219 m)) sites, but relative abundance (captures per person, per hour) at low-elevation sites was roughly twice that at high elevation
the Grider Population of the Siskiyou Mountains salamander and the Scott Bar salamander. They found occupancy rates (presence or absence) to be similar at high-elevation (greater than 4,000 feet (ft) (1,219 meters (m)) sites and low-elevation (less than 4,000 ft (1,219 m)) sites, but relative abundance (captures per person, per hour) at low-elevation sites was roughly twice that at high elevation. The authors conducted a single survey visit per site during one season, and did not evaluate the potential effect of variable detection probabilities at different elevations on their results, which, as noted above, may underestimate the number of animals actually present; however, their findings suggest that these salamanders may be less abundant or less detectable at higher elevations.
Population Size and Trend
Evaluation of potential population sizes for the Siskiyou Mountains salamander and Scott Bar salamander is strongly influenced by the species' low detectability and the amount and distribution of potentially suitable habitat. Because of their secretive habits, detection rates for these salamanders are very low, even though the species may be locally quite abundant (Nussbaum 1974, p. 3; Clayton et al. 1999, p. 133). Results of surveys within habitat known to be occupied are frequently negative (Clayton et al. 2004, p. 10; CDFG 2005, p. 10). Individual populations likely range in size from a few individuals to thousands of individuals (Nussbaum 1974, p. 16; Welsh and Lind 1992, p. 96). Based on extrapolation of salamander densities obtained during intensive field surveys, Nussbaum (1974, p. 16) provided a species-wide “conservative estimate” of over 3 million Siskiyou Mountains salamanders, and opined that the actual abundance could be 10 times as high. While the author acknowledged that a number of methodological problems may affect this estimate, it nonetheless suggests that the perceived rarity of this species may be more related to low detectability than to actual population size
16) provided a species-wide “conservative estimate” of over 3 million Siskiyou Mountains salamanders, and opined that the actual abundance could be 10 times as high. While the author acknowledged that a number of methodological problems may affect this estimate, it nonetheless suggests that the perceived rarity of this species may be more related to low detectability than to actual population size.
Our current understanding of population sizes for Siskiyou Mountains salamander and Scott Bar salamander is based primarily on the cumulative number of occupied sites or locations that have been reported over time. However, these numbers may be misleading for several reasons. At many locations, particularly sites detected during project surveys under Survey and Manage Guidelines, no attempt was made to determine population size; detection of a single individual was adequate to define an occupied site. Because of this, large habitat patches potentially supporting many individual salamanders are counted as equivalent to small habitat patches or detections of dispersing individuals. In addition, large areas of suitable habitat remain unsurveyed, particularly in Wilderness, Roadless Areas, and Late-successional Reserves where access is poor or project surveys are typically not conducted (Late-successional Reserves are a NWFP land allocation designed to serve as habitat for late-successional- and old-growth-related species). For example, approximately 10 percent and 26 percent of the range of the Scott Bar salamander and Grider salamander, respectively, is classified as “Roadless Area.” Finally, known locations are frequently spatially clumped, and no uniform effort to distinguish between individual populations has been undertaken
ion designed to serve as habitat for late-successional- and old-growth-related species). For example, approximately 10 percent and 26 percent of the range of the Scott Bar salamander and Grider salamander, respectively, is classified as “Roadless Area.” Finally, known locations are frequently spatially clumped, and no uniform effort to distinguish between individual populations has been undertaken. Agencies and researchers involved with these species employ several criteria (e.g., 164 to 492 ft (50 to 150 m) spacing, presence of perennial stream or area of unsuitable habitat) to imply separation between occupied locations or “populations.” For these reasons, the currently known numbers of Siskiyou Mountains salamanders and Scott Bar salamanders are more representative of the distribution and intensity of survey efforts than of actual salamander populations.
The numbers of known locations of Siskiyou Mountains salamanders and Scott Bar salamanders have increased steadily since the discovery of these species. For example, the number of known locations of Scott Bar salamanders on lands managed by Timber Products Company increased from 8 in 1997 to 36 in 2007 (Farber 2007c). To describe the number and distribution of known salamander locations, we obtained location data from Federal and State agencies and private timber companies and combined them into a single GIS layer. Because of variability in methods used by various agencies to delineate individual locations (many locations were clumped less than 328 ft (100 m) apart), we evaluated the proximity of adjacent locations and retained only locations greater than 328 ft (100 m) apart, to minimize the inclusion of multiple records at discrete locations. The resulting numbers are intended to represent individual populations, but likely still contain multiple records from large habitat patches and likely differ from previous estimates based on dissimilar mapping methods
we evaluated the proximity of adjacent locations and retained only locations greater than 328 ft (100 m) apart, to minimize the inclusion of multiple records at discrete locations. The resulting numbers are intended to represent individual populations, but likely still contain multiple records from large habitat patches and likely differ from previous estimates based on dissimilar mapping methods.
Within each of the genetic subunits in the Siskiyou Mountains salamander Complex, the number of locations with individuals that have been genetically confirmed to the species level is much smaller than the overall number of known locations. For example, the estimated range of the Scott Bar salamander is defined on the basis of 23 genetically confirmed locations from the samples of Mahoney, Mead, and DeGross; however, the defined range of the species contains 98 additional salamander locations previously attributed to the Grider salamander. Because populations of the two species tend not to overlap (Mead 2006, p. 10), it is reasonable to conclude that all salamander detections within what is now known to be the range of the Scott Bar salamander are Scott Bar salamanders. For the purposes of this finding, we used the total number of individual locations within each species' range, recognizing that ongoing genetic studies may modify the boundaries of these subunits, and therefore the number of known individual sites within each genetic subgroup.
Table 2.—Number of Known Locations and Percent of Total Known Siskiyou Mountains Salamanders (SMS) and Scott Bar Salamanders (SBS) on Federal and Private Lands Applegate SMS Grider SMS Scott Bar salamander 1 SMS-SBS complex Federal lands 376 (85%) 74 (97%) 69 (60%) 519 (82%) Private Lands 64 (14%) 2 (3%) 46 (40%) 112 (18%) Total 440 76 115 631 1 Number of known Plethodon sp. locations within the presumed range of the Scott Bar salamander. Density
Population densities for the Siskiyou Mountains salamander Complex are poorly known
deral and Private Lands Applegate SMS Grider SMS Scott Bar salamander 1 SMS-SBS complex Federal lands 376 (85%) 74 (97%) 69 (60%) 519 (82%) Private Lands 64 (14%) 2 (3%) 46 (40%) 112 (18%) Total 440 76 115 631 1 Number of known Plethodon sp. locations within the presumed range of the Scott Bar salamander. Density
Population densities for the Siskiyou Mountains salamander Complex are poorly known. Estimation of population density for these salamanders is hindered by low detectability and highly variable environmental or habitat conditions during surveys (Nussbaum 1974, p. 15). Densities recorded during the habitat associations study conducted by Ollivier et al. (2001, p. 16) ranged from 1 to 13 animals per 527-ft 2 (49-m 2 ) search plot (i.e., 0.02 to 0.33 animals per m 2 ); whereas Nussbaum (1974, p. 16) recorded 0.53 animals per m 2 during an intensive field study. Nauman and Olson (2007, p. 19) reported an average of 0.01 salamanders per m 2 and 2.39 salamanders per person, per hour in California, with capture rates ranging from 2.83 salamanders per person, per hour at lower elevations to 1.25 salamanders per person, per hour at higher elevation sites. An inventory of all known Siskiyou Mountains salamander sites on the Applegate Ranger District in 1992 reported abundances of salamanders ranging from 0.3 to 11 salamanders per person, per hour (Olson et al. 2007, p. 13). None of these studies was designed to estimate salamander density, and mark-recapture studies that would permit estimation of density have not been conducted.
Population Trend
We were unable to locate any information describing population trends for the Scott Bar salamander or Siskiyou Mountains salamander (or either of its constituent populations). Several authors have inferred population declines based on observations of habitat modification within occupied areas (Ollivier et al. 2001, p. 5; Welsh 2005, pp. 5-7), but their study design did not support this type of inference
e unable to locate any information describing population trends for the Scott Bar salamander or Siskiyou Mountains salamander (or either of its constituent populations). Several authors have inferred population declines based on observations of habitat modification within occupied areas (Ollivier et al. 2001, p. 5; Welsh 2005, pp. 5-7), but their study design did not support this type of inference.
Land Management
Populations of Siskiyou Mountains salamanders and Scott Bar salamanders receive an added layer of security from several conservation efforts on Federal lands. The majority of the Siskiyou Mountains salamander Complex occurs within lands administered under the provisions of the NWFP (USDA and USDI 1994) (see Table 1 above), which was established to provide an ecosystem-based management strategy for late-successional forests and the wildlife species that inhabit them (USDA and USDI 1994). The NWFP consists of two primary parts that concern salamander conservation: (1) A system of land-use allocations with associated Standards and Guidelines to guide land management; and, (2) until recently, the Survey and Manage Mitigation Measure Standards and Guidelines, which provided species-specific management guidance for certain groups of species. The NWFP Record of Decision (ROD) was implemented as amendments to all existing land and resource management plans for the Bureau of Land Management (BLM) and USFS within the range of the northern spotted owl.
Lands administered by the USFS and BLM are divided into five primary categories of land management under the NWFP: Late-successional Reserves, Congressionally Reserved Areas, Riparian Reserves, Adaptive Management Areas, and Matrix. Late-successional Reserves are established with an objective to protect and enhance conditions of late-successional and old-growth forest ecosystems, which serve as habitat for late-successional, forest-related species. Forest management activities are highly restricted within Late-successional Reserves
rves, Congressionally Reserved Areas, Riparian Reserves, Adaptive Management Areas, and Matrix. Late-successional Reserves are established with an objective to protect and enhance conditions of late-successional and old-growth forest ecosystems, which serve as habitat for late-successional, forest-related species. Forest management activities are highly restricted within Late-successional Reserves. Congressionally Reserved Areas, such as Wilderness Areas, Wild and Scenic Rivers, and National Monuments, are incorporated into the design of the Late-successional Reserve System. Riparian Reserves provide an area along all streams, wetlands, lakes, ponds, and unstable areas where riparian-dependant resources receive primary management emphasis. Maintenance of forested conditions in Riparian Reserves for shading and water quality is also expected to contribute to dispersal and breeding habitat for late-successional species. Adaptive Management Areas (AMAs) are established to develop and test new management approaches and timber harvest methods to integrate and achieve ecological and economic health, and other social objectives. Matrix lands consist of those Federal lands outside of the four other categories described above. Production of timber and other commodities is an important objective for Matrix lands. However, forests in the Matrix also provide connectivity between Late-successional Reserves and function as habitat for a variety of forest-dwelling species. The NWFP Matrix Standards and Guidelines are designed to provide for important ecological functions such as dispersal of organisms, carryover of some species from one stand to the next, and maintenance of ecologically valuable structural components such as logs, snags, and large trees. The Matrix also provides ecological diversity by providing early-successional habitat
of forest-dwelling species. The NWFP Matrix Standards and Guidelines are designed to provide for important ecological functions such as dispersal of organisms, carryover of some species from one stand to the next, and maintenance of ecologically valuable structural components such as logs, snags, and large trees. The Matrix also provides ecological diversity by providing early-successional habitat. Within Matrix, other land use allocations such as Visual Emphasis Areas, Managed Wildlife Areas, and Retention Areas carry additional restrictions on timber harvest and to some degree function as reserves.
Table 3.—Federal Land Allocations Within the Estimated Ranges of the Siskiyou Mountains Salamander (SMS) and Scott Bar Salamander (SBS) Applegate SMS Grider SMS Scott Bar salamander SMS-SBS complex Total area in ac (ha) 248,870 (100,712) 174,285 (70,529) 136,740 (55,335) 559,895 (226,578) Private Lands (%) 15 9 22 15 Federal Lands (%): Reserves 33 73 51 50 Adaptive Management Area 1 42 0 0 19 Matrix-retention 2 1 13 19 9 Matrix-general forest 3 9 5 8 7 1 Experimental management to meet ecological, economic, and social goals. 2 Timber harvest restricted to accommodate various other management goals. 3 Timber production is a high priority. Roughly 33 percent of the range of the Applegate salamander occurs within reserves (Late-successional Reserves, Wilderness, Riparian Reserves, and other land allocations withdrawn from scheduled timber harvest), 42 percent of the range within the Applegate Adaptive Management Area, 9 percent in Matrix, and 15 percent on private lands (see Table 3 above). Nearly three-quarters of the range of the Grider salamander is in reserves, and 18 percent is in Matrix; however, almost three-fourths of the Matrix is in land-use allocations (retention areas) where timber harvest is restricted (USDA 1994, pp. 4-73 to 4-176)
ercent of the range within the Applegate Adaptive Management Area, 9 percent in Matrix, and 15 percent on private lands (see Table 3 above). Nearly three-quarters of the range of the Grider salamander is in reserves, and 18 percent is in Matrix; however, almost three-fourths of the Matrix is in land-use allocations (retention areas) where timber harvest is restricted (USDA 1994, pp. 4-73 to 4-176). Fifty-one percent of the Scott Bar salamander's range is in reserves, and an additional 19 percent occurs within retention areas (Wild and Scenic Rivers, Retention Visual Quality Objective). Overall, only approximately 14 percent of the range of the Applegate salamander, 24 percent of the range of the Grider salamander, and 30 percent of the range of the Scott Bar salamander are composed of Matrix-General Forest and private timberlands, where intensive timber management would be expected to occur. However, because varying levels of timber management occur within the Applegate Adaptive Management Area in the range of the Applegate salamander, up to about 66 percent of this species' range is available for various levels of timber harvest and cannot be considered to be reserve lands.
Little is known about the actual distribution of salamander populations among the land-use allocations described above. Nauman and Olson (2007) attempted to evaluate the occurrence of Grider salamanders and Scott Bar salamanders by conducting surveys at a stratified random sample of points in reserved and matrix land allocations at high (greater than 4,000 ft (1,219 m)) versus low (less than 4,000 ft (1,219 m)) elevation. They found that capture rates for these species were higher on matrix lands, likely because a higher proportion of reserved lands occur at higher elevations, which are less suitable for the species
nders by conducting surveys at a stratified random sample of points in reserved and matrix land allocations at high (greater than 4,000 ft (1,219 m)) versus low (less than 4,000 ft (1,219 m)) elevation. They found that capture rates for these species were higher on matrix lands, likely because a higher proportion of reserved lands occur at higher elevations, which are less suitable for the species. The authors concluded that reserved land allocations may not provide adequately for conservation of the species but described a number of sampling issues (single-visit protocol, unequal sampling of strata) that may weaken this conclusion.
Survey and Manage Mitigation Measure Standards and Guidelines
In addition to the NWFP's system of land-use allocations and management standards and guidelines, specific mitigation measures were included for about 400 rare or poorly known species. We refer to this broadly as the Survey and Manage Program. The Survey and Manage Program contains an adaptive management provision, establishing the Species Review Process wherein species experts (“taxa teams”) evaluate and synthesize the latest information about each species. Reports from the taxa teams are then used by the agencies to propose changes to management of these taxa, as appropriate. The Siskiyou Mountains salamander was included in the original list of Survey and Manage species under Survey Strategies 1 and 2 (USDA and USDI 1994, pp. C-59, C-45). Survey and Manage guidelines for these salamanders required that known salamander sites be managed via protection buffers (Strategy 1), and that surveys be conducted prior to ground-disturbing activities such as timber harvest (Strategy 2). Protection buffer standards and guidelines for Siskiyou Mountains salamanders required the retention of all overstory trees within a buffer of at least the height of one site-potential tree or 100 feet horizontal distance, whichever is greater, surrounding the location
ion buffers (Strategy 1), and that surveys be conducted prior to ground-disturbing activities such as timber harvest (Strategy 2). Protection buffer standards and guidelines for Siskiyou Mountains salamanders required the retention of all overstory trees within a buffer of at least the height of one site-potential tree or 100 feet horizontal distance, whichever is greater, surrounding the location. As a result of the 1999 Species Review Process, the Siskiyou Mountains salamander was reclassified as a Category C species in the Final Supplemental Environmental Impact Statement (FSEIS) for the NWFP (USDA and USDI 2000, Appendix F; p. 101). Criteria for including a taxon in Category C are: (1) There is not a high concern for persistence; (2) it is likely that not all known sites are necessary for reasonable assurance of persistence of the taxon; (3) the taxon is uncommon (as opposed to rare); and (4) pre-disturbance surveys are required until a population network is established. The management objective for the Siskiyou Mountains salamander under Category C is to identify and manage high-priority sites to provide for reasonable assurance of persistence. The current status of the Siskiyou Mountains salamander was assigned in the March 14, 2003, Implementation of the 2002 Annual Species Review Memorandum (USDA and USDI 2003). Because of their smaller number of known sites and patchy distribution, salamander populations south of the Siskiyou Crest were assigned to Category A, requiring pre-disturbance surveys and management of protection buffers for all known sites. Northern populations were assigned to Category D. Management objectives for Category D species are to identify and manage high-priority sites to provide for a reasonable assurance of species persistence; pre-disturbance surveys are not required
ations south of the Siskiyou Crest were assigned to Category A, requiring pre-disturbance surveys and management of protection buffers for all known sites. Northern populations were assigned to Category D. Management objectives for Category D species are to identify and manage high-priority sites to provide for a reasonable assurance of species persistence; pre-disturbance surveys are not required.
The USFS and BLM have determined to remove the Survey and Manage Program, and in July 2007 published their Record of Decision (2007 ROD) to implement this decision (see “Summary of Factors Affecting the Species: Factor D”). Therefore, at this time, the Survey and Manage Program has been eliminated for project planning and new decisions. However, because of the lag time in implementation of the 2007 ROD, most new Federal land management decisions issued in 2008 will be compliant with the Survey and Management guidance for the Siskiyou Mountains salamander (West 2007); implementation of new projects compliant with the 2007 ROD is unlikely until 2009. We therefore view
The Survey and Manage guidelines have provided additional security for salamander populations across the vast majority of the range of the Siskiyou Mountains salamander. With the removal of the Survey and Manage Guidelines under the 2007 ROD, management of these species will be based on the USFS's Special Status Species Program and the BLM's Sensitive Species Program (Hughes 2007). The Special Status Species and Sensitive Species programs are anticipated to provide less stringent protections than those in the Survey and Manage Program; however, they include provisions for development of Conservation Strategies and Conservation Agreements.
Based on ecological and management information in the Annual Species Reviews and strategic surveys, the taxa team joined with additional species experts to formalize the Survey and Manage Program objectives for Siskiyou Mountains salamander
ections than those in the Survey and Manage Program; however, they include provisions for development of Conservation Strategies and Conservation Agreements.
Based on ecological and management information in the Annual Species Reviews and strategic surveys, the taxa team joined with additional species experts to formalize the Survey and Manage Program objectives for Siskiyou Mountains salamander. In anticipation of the eventual removal of the Survey and Manage Program, they developed their management recommendations into a Conservation Strategy for Siskiyou Mountains Salamanders in the Northern Portion of the Range (Olson et al. 2007). The USFS and BLM committed to implement this Conservation Strategy in the August 16, 2007, Conservation Agreement for the Siskiyou Mountains Salamander ( Plethodon stormi ) in Jackson and Josephine Counties of southwest Oregon and in Siskiyou County of northern California (USDA and USDI 2007; USDI 2007b).
In accordance with management objectives for Category D species, the Conservation Strategy relies on long-term management of a subset of known salamander sites. A panel of scientists and resource managers selected high-priority sites and considered a number of criteria including existing Federal Standards and Guidelines for the planning area, distribution and quality of habitat, known locations of salamanders, and potential risk factors such as fire hazard, road density, and land ownership. To ensure the existence of well-distributed, interacting subpopulations, these criteria were evaluated at three spatial scales: The entire Applegate River watershed, 19 smaller watersheds within the Applegate River watershed, and individual sites. Of 316 known salamander locations on Federal lands, 151 (48 percent) were included in the 110 high-priority salamander management areas selected (some management areas encompassed multiple salamander sites). Of the 110 selected sites, 44 are on BLM lands and 66 are on the Rogue River-Siskiyou National Forest
tershed, 19 smaller watersheds within the Applegate River watershed, and individual sites. Of 316 known salamander locations on Federal lands, 151 (48 percent) were included in the 110 high-priority salamander management areas selected (some management areas encompassed multiple salamander sites). Of the 110 selected sites, 44 are on BLM lands and 66 are on the Rogue River-Siskiyou National Forest. Each high-priority salamander-management site is intended to maintain a subpopulation of Siskiyou Mountains salamanders over the long term (100 years). Because habitat-disturbing activities are regulated to varying degrees across the entire NWFP area occupied by the salamanders, the scientists who developed the strategy anticipate that many additional populations will continue to persist in reserved lands and in Matrix where habitat is retained for other reasons (Olson et al. 2007, p. 21).
Each high-priority salamander-management site was evaluated for application of one of two management strategies. The first strategy focuses on maintaining habitat conditions for salamanders at the site by limiting activities that may have adverse effects on substrate, ground cover, forest condition, or microhabitat and microclimate. The second strategy allows for greater latitude in activities at the high-priority site by applying the existing National Fire Plan Fire Management Recommendations to the high-priority site. This two-tiered approach attempts to integrate the fire ecology of the area, current forest conditions, fuel loads, and proximity to populated areas while providing for the persistence of Applegate salamander populations over the long term.
The Conservation Strategy contains a rigorous risk assessment (Olson et al. 2007, p. 22 and Appendix 2), which concludes that implementation of the Strategy presents an extremely low risk to the species' persistence at the range-wide scale
nt forest conditions, fuel loads, and proximity to populated areas while providing for the persistence of Applegate salamander populations over the long term.
The Conservation Strategy contains a rigorous risk assessment (Olson et al. 2007, p. 22 and Appendix 2), which concludes that implementation of the Strategy presents an extremely low risk to the species' persistence at the range-wide scale. This conclusion is based on evaluation of the comparative risk of losses of individuals or subpopulations due to fuels management activities versus higher risk of losses if high-intensity wildfires occur at untreated sites. Other risks posed by other forest management activities are ameliorated by the protection-buffer approach adopted from current Survey and Manage guidance. Redundancy of protected sites and a mix of protective and restoration approaches across the entire range of the Applegate salamander also act to increase the likelihood of persistence over the long term.
The Conservation Strategy was authored by four of the most published scientific experts on this species (D. Olson, D. Clayton, H. Welsh, and R. Nauman, among others), and incorporates habitat modeling and risk assessment in the evaluation of species persistence and distribution within the strategy area. The Conservation Strategy also contains provisions to support monitoring and strategic surveys to address gaps in our knowledge of the species and its conservation. Funding for these efforts is anticipated to come from the USFS and BLM's Special Status Species programs. Implementation and effectiveness of this Conservation Strategy will be reviewed every five years by BLM, USFS, and the Service. Based on these regular reviews, or significant information that may become available between the five-year reviews, the Conservation Strategy may be revised to refine the plan or address emerging issues
ated to come from the USFS and BLM's Special Status Species programs. Implementation and effectiveness of this Conservation Strategy will be reviewed every five years by BLM, USFS, and the Service. Based on these regular reviews, or significant information that may become available between the five-year reviews, the Conservation Strategy may be revised to refine the plan or address emerging issues.
In anticipation of the discontinuation of the Survey and Manage Program, biologists from the Klamath National Forest (KNF) and the Service's Yreka Fish and Wildlife Office (YFWO) are developing a Conservation Strategy to guide management of both Grider and Scott Bar salamander populations on lands administered by the KNF. This Strategy would apply to over 90 percent of the range of the Grider salamander DPS, and 78 percent of the Scott Bar salamander's range. The draft KNF Strategy does not require surveys to be conducted prior to ground-disturbing activities; instead, all suitable salamander habitat (talus substrate) is assumed to be occupied and managed for long-term persistence of salamander populations. Similar to the Conservation Strategy for Applegate salamanders (Olson et al. 2007), the draft KNF Strategy balances protection of existing suitable habitat with active management of risks such as hazardous fuels. Small habitat patches (less than 5 ac (2 ha)) and locations with high likelihood of occupancy by salamanders (lower slopes, northerly exposures) receive strict protective guidelines; whereas habitat patches on upper slopes with southerly exposures may receive fuels reduction treatments that reduce canopy closure to a limited degree.
As discussed below in Factor D, we are not relying on implementation of the Conservation Strategies in making our determination that listing the Siskiyou Mountains salamander and Scott Bar salamander is not warranted
strict protective guidelines; whereas habitat patches on upper slopes with southerly exposures may receive fuels reduction treatments that reduce canopy closure to a limited degree.
As discussed below in Factor D, we are not relying on implementation of the Conservation Strategies in making our determination that listing the Siskiyou Mountains salamander and Scott Bar salamander is not warranted. We have included this discussion solely as background for the public and to acknowledge USFS and BLM efforts to
Summary of Factors Affecting the Species
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations at 50 CFR part 424 set forth procedures for adding species to the Federal List of Endangered and Threatened Wildlife. In making this finding, we summarize below, information regarding the status and threats to this species in relation to the five factors in section 4(a)(1) of the Act. In making our 12-month finding, we considered and evaluated all scientific and commercial information in our files, including information received during the public-comment period that ended May 29, 2007.
Siskiyou Mountains Salamander
Factor A: The Present or Threatened Destruction, Modification, or Curtailment of the Species' Habitat or Range
Like other plethodontids, Siskiyou Mountains salamanders require moisture for respiration (Nussbaum et al. 1983, pp. 73, and 90). This physiological requirement limits the time during which they are active at the soil's surface to relatively brief, rainy periods in the spring and fall (Nussbaum et al. 1983, pp. 102-103; Clayton et al. 1999, p. 133). These salamanders engage in important behaviors, including foraging and breeding, during periods of surface activity (Feder 1983, p. 296). During the remainder of the year, they retreat into rocky substrates, which provide refuge from the climatic extremes of the eastern Klamath Mountains (Nussbaum et al. 1983, p. 102)
ring and fall (Nussbaum et al. 1983, pp. 102-103; Clayton et al. 1999, p. 133). These salamanders engage in important behaviors, including foraging and breeding, during periods of surface activity (Feder 1983, p. 296). During the remainder of the year, they retreat into rocky substrates, which provide refuge from the climatic extremes of the eastern Klamath Mountains (Nussbaum et al. 1983, p. 102). Given their physiology and life histories, disturbances that reduce surface and soil moisture, relative humidity, or suitable rocky substrates may negatively affect these species. Disturbances that possibly impact Siskiyou Mountains salamanders include timber harvesting, fires, road construction, mining, and quarrying.
Effects of Timber Harvesting on Siskiyou Mountains Salamanders
Timber harvesting may impact Siskiyou Mountains salamander by killing individuals or by reducing habitat quality. Ollivier et al. (2001, pp. 41-42) and Welsh et al. (2007a, p. 28) found that Siskiyou Mountains salamanders were associated with characteristics found in mature forests, such as dense canopy cover, large-diameter trees, and mossy ground cover. Other studies have shown that Siskiyou Mountains salamanders occur within a wide range of forest conditions, including in recently clear-cut sites and in open-canopy forest (e.g., Bull et al. 2006, p. 24; Farber et al. 2001, p. 13; Farber 2007, p. 3). The conclusions of these studies do not necessarily conflict since it is possible that these salamanders occur within a wide range of habitat conditions while selectively using or receiving greater fitness from a subset of them, or are more easily detected in a subset of them. Alternatively, these species may select habitat based on attributes that are not dependent on forest age or structural class. For example, they may select habitat with cool, moist microclimates, which are common in mature forests but also occur under other conditions (e.g., in deep drainages or on north-facing slopes)
fitness from a subset of them, or are more easily detected in a subset of them. Alternatively, these species may select habitat based on attributes that are not dependent on forest age or structural class. For example, they may select habitat with cool, moist microclimates, which are common in mature forests but also occur under other conditions (e.g., in deep drainages or on north-facing slopes). The paucity of rigorous scientific information about Siskiyou Mountains salamanders makes an accurate evaluation of their habitat associations (see Habitat Associations section above) and sensitivities to timber harvesting difficult. Information about the effects of timber harvesting on this species is currently limited to inferences based on the physiology of this species, two studies of the effects of timber harvesting on Siskiyou Mountains salamanders, and extrapolation of inferences from studies of the effects of timber harvesting on other species of plethodontid salamanders.
Timber harvesting may negatively affect Siskiyou Mountains salamander by reducing soil moisture and increasing soil temperature. Studies by Chen et al. (1993, pp. 233-234; 1995, pp. 77-82; 1999, pp. 292-294) in Pacific Northwest Douglas fir forests found that both soil and air were drier and warmer in clear cuts and clear-cut forest edges than in adjacent old-growth forest. These results indirectly suggest that clear-cutting may negatively affect these animals. We are not aware of any studies on the effects of other silvicultural techniques on forest microclimates. However, alternative even-age harvesting techniques (shelterwood and seed-tree cuts), uneven-age harvesting (single tree and group selection harvesting), and thinning retain more canopy cover than does clear-cutting and, therefore, probably have lower impacts on forest microclimates
e animals. We are not aware of any studies on the effects of other silvicultural techniques on forest microclimates. However, alternative even-age harvesting techniques (shelterwood and seed-tree cuts), uneven-age harvesting (single tree and group selection harvesting), and thinning retain more canopy cover than does clear-cutting and, therefore, probably have lower impacts on forest microclimates. The effects of timber harvesting also strongly depend on the silvicultural prescription (e.g., the volume of wood removed and the size, volume, and distribution of retained trees, snags, and logs) and on site-specific factors (e.g., climate and slope aspect). We expect that the effects of silviculture on Siskiyou Mountains salamander depend primarily on the intensity and scale of the disturbance.
We are aware of two studies analyzing the effects of timber harvesting on Siskiyou Mountain salamanders. The first was conducted in Siskiyou County, California by the USFS (D. Clayton, cited in Bull et al. 2006, p. 21; Olson et al. 2007, p. 16). This study compared abundances of Siskiyou Mountains salamanders through time at a clear-cut site and an adjacent selectively cut site. In the clear-cut site, the researchers found 40 salamanders (10 salamanders per person, per hour) the spring after the harvest, one juvenile the following year, no animals in the subsequent 7 years, and one juvenile during an opportunistic survey in the tenth year. In comparison, they consistently found 3 to 6 salamanders per person, per hour in the selectively cut site during the same years sampled (Bull et al. 2006, p. 21). The CDFG resurveyed the same clear-cut site in the spring and fall of the eleventh year post-harvest (Bull et al. 2006, p. 21). Single surveyors found 10.6 salamanders per person, per hour in the spring and 4.25 salamanders per person, per hour in the fall
consistently found 3 to 6 salamanders per person, per hour in the selectively cut site during the same years sampled (Bull et al. 2006, p. 21). The CDFG resurveyed the same clear-cut site in the spring and fall of the eleventh year post-harvest (Bull et al. 2006, p. 21). Single surveyors found 10.6 salamanders per person, per hour in the spring and 4.25 salamanders per person, per hour in the fall. This result suggests that, while Siskiyou Mountains salamanders may be negatively impacted by intensive timber management practices such as clear-cutting, they are able to recover in, or recolonize, some clear-cuts as vegetation recovers. As importantly, less intensive harvest methods may have less impact on salamander abundance. However, inferences from both sets of surveys are highly limited because the surveys did not include pre-harvest data and were conducted in only one pair of plots.
In a nearby area, Fruit Growers Supply Company monitored Siskiyou Mountains salamanders on the Elliot Fly Timber Harvesting Plan. They monitored salamanders on 39 plots (35 harvested and 4 controls). The harvesting method was a selective cut, and logs were removed by helicopter, a method which significantly reduces the amount of ground disturbance. Plots were surveyed prior to harvest, 1 year post-harvest, and 10 years post-harvest (Taylor 2007, p. 1). Estimates of relative abundance (count data) in the harvested plots ranged from 1.8 to 2.0 captures per survey compared to 2.0 to 3.2 captures per survey in unharvested controls, and did not significantly change during the study. These results suggest that the harvest did not significantly adversely affect the salamanders (Taylor 2007, p. 3). The determination of no significant difference between treatments and control plots was likely influenced by the high variability observed within and
All life-history stages of Siskiyou Mountains salamander, including gravid females (carrying eggs), have been found in open-canopy forest and recent clear-cuts (Farber et al. 2001, p
gnificantly adversely affect the salamanders (Taylor 2007, p. 3). The determination of no significant difference between treatments and control plots was likely influenced by the high variability observed within and
All life-history stages of Siskiyou Mountains salamander, including gravid females (carrying eggs), have been found in open-canopy forest and recent clear-cuts (Farber et al. 2001, p. 13; Bull et al. 2006, p. 24; Farber 2007, p. 3). However, little is known about relationships between forest conditions and the population dynamics of the Siskiyou Mountains salamander. Welsh et al. (2007b) analyzed relationships between forest age class and the age structure and body condition of both Siskiyou Mountains salamanders and Scott Bar salamanders. All salamander age classes were found in pre-canopy (0 to 33 years) sites, but 8 of 11 individuals detected in those sites were juveniles or subadults. If representative of population age structure, this observation could indicate that pre-canopy sites function as ‘sink’ or dispersal habitat for non-reproductive individuals. Alternatively, high proportions of juveniles could indicate high reproductive rates and population recovery following logging. Sample sizes were too small to test these hypotheses. Welsh et al. (2007b) also found that Siskiyou Mountains salamanders in mature (100 to 199 years) sites had significantly higher median body condition (ratio of body mass to length) than those in young sites (31 to 99 years). This could indicate that young forest stands provide lower quality habitat than mature stands.
Timber harvesting could also affect Siskiyou Mountains salamanders at spatial scales larger than individual salamander sites. The petition to list the Siskiyou Mountains salamander (Center for Biological Diversity et al. 2004, p. 8) asserts that timber harvesting creates gaps in the distribution of this species because it is rarely able to recolonize habitat after local populations are extirpated
Timber harvesting could also affect Siskiyou Mountains salamanders at spatial scales larger than individual salamander sites. The petition to list the Siskiyou Mountains salamander (Center for Biological Diversity et al. 2004, p. 8) asserts that timber harvesting creates gaps in the distribution of this species because it is rarely able to recolonize habitat after local populations are extirpated. Indirectly supporting this hypothesis, studies of the closely related Del Norte salamander showed that it is highly sedentary and, therefore, likely to have limited dispersal abilities. Welsh and Lind (1992, p. 427) reported that the longest movement by an individual Del Norte salamander was 119 ft (36.2 m) over 6 months, and Lowe (2001, p. 27) found that the longest movement was 129.9 ft (39.6 m) over 2 years. Average movements were substantially smaller than these: 22 ft (6.7 m) over 2 years (Lowe 2001, p. 27) and 16.7 ft (5.1 m) over 6 months (Karraker and Welsh 2006, p. 136). Siskiyou Mountains salamanders, and in particular Scott Bar salamanders, have relatively longer limbs than Del Norte salamanders and may be capable of longer movements, but their dispersal abilities are still likely limited. Some researchers have suggested that dispersing juvenile Siskiyou Mountains salamanders readily colonize logged sites (Welsh 2005, pp. 1-2) and road cutbanks (Nussbaum 1974, p. 13). Alternatively, it is possible that salamanders in regenerating logged sites and road cutbanks are indicative of population persistence and recovery following disturbance, rather than extirpation and subsequent recolonization.
Welsh and Ollivier (1995, pp. 8-9) suggested that tractor yarding of logs during timber harvesting may impact Siskiyou Mountains salamanders by compacting, breaking, or realigning talus. If tractor yarding has these effects, it could reduce the interstitial spaces in talus and thereby reduce habitat quality for these species
ing disturbance, rather than extirpation and subsequent recolonization.
Welsh and Ollivier (1995, pp. 8-9) suggested that tractor yarding of logs during timber harvesting may impact Siskiyou Mountains salamanders by compacting, breaking, or realigning talus. If tractor yarding has these effects, it could reduce the interstitial spaces in talus and thereby reduce habitat quality for these species. Although it is reasonable to conclude that tractor yarding may disturb talus substrates, research has not demonstrated how this affects salamander populations.
In summary, rigorous research of the effects of timber harvesting on Siskiyou Mountains salamanders is needed, but intensive timber harvesting practices, such as clear-cutting and tractor yarding, appear to have negative short-term (30 years or less) effects on abundance, population structure, and body condition of these species (Welsh et al. 2007b). Intensive timber harvesting likely affects these salamanders by changing forest characteristics that influence microclimates for them, for example, by opening the forest overstory and understory canopies and reducing coverage of down wood and leaf litter. Despite these effects, it is also clear that the salamanders frequently persist in intensively harvested habitats, and there is no information suggesting that populations are permanently extirpated by timber harvest. It is unknown whether these salamanders may be temporarily extirpated from severely disturbed sites or simply retreat underground during the initial period of post-disturbance recovery. Alternative silvicultural techniques, such as thinning, selective harvesting, and helicopter yarding, appear to be less harmful to these salamanders than more intensive harvesting methods.
Timber Harvesting Effects on Other Plethodontids
To support their assertion that the Siskiyou Mountains salamander is threatened by timber harvesting, the petitioners cite studies of other closely related species
native silvicultural techniques, such as thinning, selective harvesting, and helicopter yarding, appear to be less harmful to these salamanders than more intensive harvesting methods.
Timber Harvesting Effects on Other Plethodontids
To support their assertion that the Siskiyou Mountains salamander is threatened by timber harvesting, the petitioners cite studies of other closely related species. Most studies of the closely related Del Norte salamander indicate that this salamander is more abundant in mature forest than in other forest age classes (Raphael 1988, p. 27; Welsh and Lind 1991, p. 400; Welsh and Lind 1995, p. 208). In contrast, Diller and Wallace (1994, p. 316) did not detect a relationship between forest age and the presence of Del Norte salamanders near the northern California coast. It is possible that forest structural characteristics (e.g., canopy cover) more strongly influence microclimates for salamanders in the interior of the Klamath Mountains than near the coast, where temperatures are more moderate and moisture is less limiting.
Karraker and Welsh (2006, p. 137) found lower abundances of Del Norte salamanders in clear-cuts than in mature stands. All salamander life stages were observed in clear-cuts, indicating that reproduction was occurring in them. Abundances were similar in commercially thinned and mature stands. Welsh et al. (2007b) found significant positive relationships between forest age class and presence and abundance of Del Norte salamanders. Adult salamanders accounted for a larger proportion of individuals observed in old-growth (older than 200 years) and mature (100 to 199 years) stands than they did in young (31 to 99 years) stands. The authors suggested that higher proportions of adult salamanders are indicative of greater population stability for this species. In contrast, salamanders at pre-canopy (0 to 33 years), young, and old-growth sites had higher median body condition than those in mature stands or the reference site (thought to be a high-quality site)
199 years) stands than they did in young (31 to 99 years) stands. The authors suggested that higher proportions of adult salamanders are indicative of greater population stability for this species. In contrast, salamanders at pre-canopy (0 to 33 years), young, and old-growth sites had higher median body condition than those in mature stands or the reference site (thought to be a high-quality site). The authors speculated that the apparent inconsistencies in their results were related to greater competition and poorer body condition in sites with higher salamander abundances, but more research is needed to test this hypothesis. Biek et al. (2002, p. 137) found similar abundances of Del Norte salamanders in clear-cuts and mature forests in Oregon, apparently contradicting the results of the studies discussed above.
Evaluation of studies of the effects of timber harvesting on plethodontids outside the Plethodon elongatus Complex may improve our
Grialou et al. (2000, pp. 108-110) found that western red-backed salamanders in mesic forests in southwestern Washington occupied recent clear-cuts (2 to 4 years post-harvest) but at significantly lower abundances than in adjacent older stands. Body sizes of salamanders (subadults and juveniles) were smaller the year after harvesting but were normal by the second year. Gravid females were captured on clear-cut plots before and after harvest. Grialou et al. (2000, p. 111) suggested that reduced abundances of western red-backed salamanders in clear-cuts were related to soil compaction, loss of woody debris, and decreased leaf litter cover associated with harvesting. Bury and Corn (1988, p. 171) reported plethodontid salamanders to be absent in four clear-cut study sites, but their results were equivocal because detection rates were very low in all of the habitats studied. In contrast to the above studies, Corn and Bury (1991, p
ders in clear-cuts were related to soil compaction, loss of woody debris, and decreased leaf litter cover associated with harvesting. Bury and Corn (1988, p. 171) reported plethodontid salamanders to be absent in four clear-cut study sites, but their results were equivocal because detection rates were very low in all of the habitats studied. In contrast to the above studies, Corn and Bury (1991, p. 311) found that abundances of western red-backed salamanders were not significantly different in recent clear-cuts (less than 10 years old) and old-growth forest.
Studies of plethodontids in the mid-western and eastern United States (Ash 1997, p. 985; deMaynadier and Hunter 1998, pp. 344-345; Herbeck and Larsen 1999, p. 626) and western Canada (Dupuis et al. 1995, p. 648) indicated that clear-cutting can have significant short-term impacts on plethodontid salamander abundance. Dupuis et al. (1995, p. 648), Ash (1997, p. 987), and Herbeck and Larsen (1999, p. 626) reported that plethodontid salamanders were frequently absent from 2- to 5-year-old clear-cut stands. However, the impact of clear-cutting on these salamanders may be temporary, as one study (Ash 1997, pp. 985-986) showed that salamanders returned to clear-cut areas 4 to 6 years after cutting, and their return was followed by rapid increases in their numbers. Statistical modeling of salamander abundances on clear-cut plots indicated that salamanders would equal or exceed numbers on forested plots by 20 to 24 years after cutting (Ash 1997, pp. 985-986). Knapp et al. (2003, pp. 754-758) used a randomized, replicated design to quantify plethodontid salamander populations on harvested timberlands of the Appalachian Mountains in Virginia and West Virginia. While salamander abundances were lower in clear-cuts than in control plots, there were no differences in the proportion of gravid females or in the average number of eggs in gravid females
85-986). Knapp et al. (2003, pp. 754-758) used a randomized, replicated design to quantify plethodontid salamander populations on harvested timberlands of the Appalachian Mountains in Virginia and West Virginia. While salamander abundances were lower in clear-cuts than in control plots, there were no differences in the proportion of gravid females or in the average number of eggs in gravid females. Moreover, there were no differences in the proportion of juvenile animals, except in one plethodontid species, which had a higher proportion of juveniles in uncut treatments.
Extent of Timber Harvesting Within the Range of the Siskiyou Mountains Salamander
Evaluation of the threat potentially posed by modification or loss of habitat via timber harvest must be based on an assessment of the biological mechanisms involved, as well as quantification of the likelihood of those mechanisms occurring to an extent and magnitude reasonably expected to result in the threat of extinction. The extent and magnitude of potential effects caused by timber harvest are strongly influenced by existing land management regulations on the majority of the species' ranges. Approximately 85 percent of the range of the Siskiyou Mountains salamander occurs on Federal lands managed under the NWFP (USDA and USDI 1994) (see Table 3 above). In general the system of reserves and management guidelines provided by the NWFP provide a substantial reduction in the likelihood of widespread habitat alteration due to timber harvesting.
The rate and extent of timber harvest has declined dramatically on Federal lands within the NWFP area during the past 30 years (USDA and USDI 2005), particularly on the Klamath National Forest, which comprises roughly 91 percent of the range of the Grider salamander. These reductions have been primarily due to the implementation of the NWFP and other Federal land management regulations
rvesting.
The rate and extent of timber harvest has declined dramatically on Federal lands within the NWFP area during the past 30 years (USDA and USDI 2005), particularly on the Klamath National Forest, which comprises roughly 91 percent of the range of the Grider salamander. These reductions have been primarily due to the implementation of the NWFP and other Federal land management regulations. During the 6-year period from 2000 to 2005, the Klamath National Forest sold and removed an average of 15.9 million board feet of timber annually, compared with 187.8 million board feet per year during 1985 to 1990 (inclusive), and 238.2 million board feet per year from 1979 to 1984; this marks a reduction of roughly 93 percent from the 1979 to 1984 period (USDA 2006a). Perhaps more importantly, the amount of intensive timber management (regeneration harvests, overstory removal) has declined sharply, from an average of 3,733 ac per year from 1988 to 1991, to 38 ac per year from 2000 to 2006. Intensive harvest prescriptions such as clear-cutting were not used in 2001 or 2002, nor in 2004 to 2006 (USDA 2007b). Likewise, timber harvest on the Rogue River National Forest (which comprises roughly 66 percent of the range of the Applegate Population of the Siskiyou Mountains salamander (Clayton 2007b) declined by 96 percent during the last 30 years. Annual timber harvest during the 1980s averaged 182 million board feet, compared with 8 million board feet per year from 2000 to 2006 (USDA 2007c). Since 1996, only one timber sale has been sold and harvested on the Rogue River National Forest's Applegate Ranger District. Timber harvest, particularly intensive harvest methods, has also declined dramatically on lands administered by the BLM within the range of Applegate salamander. Mean annual harvest on the BLM's Ashland Resource Area have declined from 2,240 ac (907 ha) per year between 1995 and 2000, to 664 ac (269 ha) per year between 2001 and 2007 (USDI 2007a)
River National Forest's Applegate Ranger District. Timber harvest, particularly intensive harvest methods, has also declined dramatically on lands administered by the BLM within the range of Applegate salamander. Mean annual harvest on the BLM's Ashland Resource Area have declined from 2,240 ac (907 ha) per year between 1995 and 2000, to 664 ac (269 ha) per year between 2001 and 2007 (USDI 2007a). Less than 270 ac (109 ha) per year have been harvested since 2003 (USDI 2007a). Intensive harvest methods, such as clear-cuts and shelterwood harvests, have declined from 54 percent of acres harvested in the mid-1990s, to less than 1 percent of the annual harvest since 2001. The implementation of the NWFP and subsequent declines in timber harvest levels on Federal lands, particularly intensive harvests thought to potentially affect salamanders, greatly reduces the likelihood that a substantial proportion of the salamanders' populations will be affected by logging. We anticipate that reduced levels of timber harvest will continue into the foreseeable future because this has been the trend for the last 30 years and we have no substantial information that indicates that this trend will be reversed in the foreseeable future. In addition, the essential goals of the NWFP remain in effect and we have no information that would lead us to anticipate changes to the overall goals of this ecosystem management strategy. The removal of the Survey and Manage guidelines is relevant only to occupied salamander sites that overlap with Federal forest management projects; this comprises a very small fraction of the NWFP area and will have an insignificant effect on the overall levels of timber harvest within the range of the Siskiyou Mountains salamander.
Intensive timber harvest methods such as clear-cutting are extremely limited in extent on Federal lands within the ranges of these salamanders, but where they occur they may reasonably be expected to have negative impacts on salamander populations
of the NWFP area and will have an insignificant effect on the overall levels of timber harvest within the range of the Siskiyou Mountains salamander.
Intensive timber harvest methods such as clear-cutting are extremely limited in extent on Federal lands within the ranges of these salamanders, but where they occur they may reasonably be expected to have negative impacts on salamander populations. The available evidence does not demonstrate that the less-intensive harvest methods commonly employed on Federal lands have had substantial impacts to salamander populations, and we do not anticipate such impacts in the future. However, we acknowledge that the relationship between degree of management intensity and effects to salamanders requires further investigation.
Intensive timber harvesting practices on private timberlands affect only 10 percent of the Siskiyou Mountains salamander's range. The majority of private lands within the salamander's range occur as small parcels (typically one square mile or less) in a checkerboard pattern surrounded by Federal lands. Salamander populations on private lands may be negatively affected by timber harvesting but are dispersed among populations on Federal lands where management is more favorable. This acts to maintain redundancy, distribution, and connectivity among Siskiyou Mountains salamander populations within the mix of Federal and private lands. In addition, surveys and monitoring of Siskiyou Mountains salamanders on private timberlands demonstrate that numerous populations of Siskiyou Mountains salamanders continue to exist post-harvest and some exhibit evidence of normal population structure (Farber et al. 2001, p. 13; Bull et al. 2006, p. 24; Farber 2007, p. 3), indicating that extirpation of salamander populations on harvested private timberlands is not a substantial threat to the species.
Wildfire
Wildfire is thought to be a potential threat to Siskiyou Mountains salamander habitat (Olson et al. 2007, pp. 15, 25-26)
rvest and some exhibit evidence of normal population structure (Farber et al. 2001, p. 13; Bull et al. 2006, p. 24; Farber 2007, p. 3), indicating that extirpation of salamander populations on harvested private timberlands is not a substantial threat to the species.
Wildfire
Wildfire is thought to be a potential threat to Siskiyou Mountains salamander habitat (Olson et al. 2007, pp. 15, 25-26). Fire suppression and logging have altered forest structure and increased fuel loading in much of the Klamath-Siskiyou region (Skinner et al. 2006, pp. 178-179). Fire regimes within the ranges of the species have largely shifted from frequent, low-to-moderate or mixed-severity fires to less frequent, more severe fires (Agee 1993, pp. 388-389; Taylor and Skinner 1998, p. 298; USDA 1999, pp. 2-76 and 2-82; Skinner et al. 2006, p. 191). However, debate exists concerning the extent to which this effect is operating in the Klamath and Siskiyou Mountains (Odion et al. 2004, pp. 933-934). Climate changes associated with global warming are expected to increase the frequency of large, severe fires in this region (see Factor E discussion below). However, fire modeling suggests that the level of tree mortality would be highly variable within the geographic ranges of these species (USDA 1999, pp. 2-76 and 2-82; Suzuki and Olson 2007, p. 8), resulting in a mosaic pattern of habitat effects. Similar mosaics of effects have been documented for large fires in other regions (e.g., Eberhart and Woodard 1987, pp. 1207-1212). In addition, the talus outcrops inhabited by these salamanders may modify the behavior of fire (e.g., Major 2005, p. 95) by acting as minor fuel breaks and influencing the mosaic of burned and unburned areas.
The direct effects of fire on these species are unknown but interstitial spaces in deeper talus habitat lik

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Source: Frix Law Library, https://www.frixlaw.com/law-library/statutes/FR_PRORULE_E8-918. Check the current official text before relying on it. Not legal advice.