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, 4380-4418 [E8-918]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 73, Number 16 (Thursday, January 24, 2008)]
[Proposed Rules]
[Pages 4380-4418]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: E8-918]



[[Page 4379]]

-----------------------------------------------------------------------

Part III





Department of the Interior





-----------------------------------------------------------------------



Fish and Wildlife Service



-----------------------------------------------------------------------



50 CFR Part 17



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; Proposed Rule

Federal Register / Vol. 73, No. 16 / Thursday, January 24, 2008 / 
Proposed Rules

[[Page 4380]]


-----------------------------------------------------------------------

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 https://
www.regulations.gov and https://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). 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). 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. 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). 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

[[Page 4381]]

Cooperative Agreement with the U.S. Geological Survey, Forest and 
Rangeland Ecosystem Science Center, in Corvallis, Oregon, to provide a 
technical report addressing taxonomy, biology, habitat associations, 
detectability, and effects of habitat alteration on the salamanders. 
The technical report was authored by Douglas DeGross and R. Bruce Bury, 
and reviewed by species experts in the U.S. Geological Survey, Forest 
and Rangeland Ecosystem Science Center; U.S. Forest Service (USFS) 
Pacific Northwest Research Station and Pacific Southwest Research 
Station; and Rogue River-Siskiyou National Forest. The technical report 
(DeGross and Bury 2007), information provided by the public, and 
additional information and data in our files provided the basis for 
this status review for the Siskiyou Mountains salamander and Scott Bar 
salamander. In addition, Service staff involved in the development of 
this finding have several years of combined experience surveying for 
and researching the distribution and habitat associations of Siskiyou 
Mountains salamander.

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.
    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 (Ne) 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. 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. 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. 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

[[Page 4382]]

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). 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. 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).
    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. 
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

[[Page 4383]]

conducted prior to recognition of the Scott Bar salamander as a 
separate species, and since both species are members of the Family 
Plethodontidae, their life histories and habitat associations appear to 
be similar. Therefore, for the purpose of this finding, we use the 
current literature describing the biological characteristics and 
ecology of the Siskiyou Mountains salamander for both species.
    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.
    (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). 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 [deg]F (4 to 20 [deg]C), soil temperatures between 38.3 and 64.4 
[deg]F (3.5 to 18 [deg]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). 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. 
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. 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

[[Page 4384]]

use Muck-a-Muck as a ``reference site,'' a location with reliable 
salamander detections that can be checked prior to conducting surveys 
in other nearby areas to confirm that current weather conditions are 
within proper limits to conduct these surveys. However, even when 
survey conditions are adequate, salamanders may not be detected at this 
known reference site on any given single visit. Located adjacent to a 
road, the site experienced hydraulic mining in the late 1800s and 
currently supports a sparse overstory of young and early mature trees. 
These habitat conditions are representative of habitat at many 
locations occupied by apparently viable populations of Siskiyou 
Mountains salamanders (Bull et al. 2006, pp. 19-22; CDFG 2005, p. 24; 
Farber 2007a, pp. 3-4). The regularly reported existence of salamander 
populations at sites like the Muck-a-Muck Creek site undercuts the 
conclusion of some researchers (based on the results of a single study) 
that the species is dependent on old-growth forest (Ollivier et al. 
2001, pp. 26-29; Welsh et al. 2007a, p. 31).
    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). 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). 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). 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. 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

[[Page 4385]]

within a relatively small area (29 acres (ac) (11.7 hectares (ha))) and 
found that salamander abundance was only significantly related to 
percent rock cover. A large proportion of the occupied sites (94 
percent) had evidence of at least one previous manmade or natural 
disturbance (Farber 2007a, p. 3). Bull et al. (2006) described CDFG 
surveys at 68 sites occupied by Siskiyou Mountains or Scott Bar 
salamanders. Eighty-seven percent of these sites were on private 
timberlands, and the remaining sites were on Federal lands (Bull et al. 
2006, p. 24). Like Farber (2007a), CDFG found evidence of previous 
disturbance at most (82 percent) occupied sites (Bull et al. 2006, p. 
24). Roughly 83 percent of the sites occurred in forest stands with 
relatively open canopies (less than 60 percent canopy closure). They 
also found that salamander sites occurred within a wide range of 
environmental conditions, including all slope aspects and nearly all 
(16 of 18) California Wildlife Habitat Relationships tree size and 
canopy classes (Bull et al. 2006, p. 24). These studies' sampling 
designs preclude inferences about the habitat preferences of other 
Siskiyou Mountains salamander populations because they were focused on 
known salamander sites and did not take into account the broad range of 
habitat that is potentially available to these salamander species. 
However, both studies showed that Siskiyou Mountains salamanders and 
Scott Bar salamanders occur within a relatively wide range of forest 
conditions, and were not extirpated by the disturbances (timber 
harvest) that created those conditions.
    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. 
(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). 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. 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. For the purposes of this 
finding, we delineated species' ranges and calculated landscape 
statistics based on

[[Page 4386]]

range boundaries proposed by Nauman and Olson (2007, p. 4) but we 
slightly modified these boundaries based on new species locations, 
watershed boundaries, and distribution of suitable habitat. Based on 
the locations of genetic samples of Scott Bar salamanders, we estimated 
its range to incorporate the southeastern portion of the former 
Siskiyou Mountains salamander's range. However, the uneven distribution 
of surveys and small number of locations with genetic confirmation 
creates uncertainty as to the actual extent of the Scott Bar 
salamander. The resulting estimated range (136,740 ac (55,335 ha)) is 
considerably larger than previous estimates that were based on a small 
number of genetically confirmed locations; some of this expansion is 
the result of confirmation of one Scott Bar salamander location in the 
Walker Creek drainage (DeGross 2007). Several watersheds in the 
southern portion of the estimated range delineated by Nauman and Olson 
(2007, p. 4) do not have records of Siskiyou Mountains or Scott Bar 
salamander locations. Review of these areas by species experts (Cuenca 
2007; Clayton 2007) indicated that surveys have not been conducted 
there, but suitable habitat is widespread. Additional surveys and 
genetic analyses are necessary to adequately delineate the southern 
boundary of the Scott Bar salamander and Siskiyou Mountains salamander. 
Our estimates of species' ranges are intended for use in evaluating 
species' distribution across various land ownership and Federal land 
allocations; they are not intended to represent precise estimates of 
occupied habitat.
    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. 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)
----------------------------------------------------------------------------------------------------------------
                                                                                         Scott Bar
                                                               Applegate    Grider SMS   salamander    SMS-SBS
                                                                SMS (%)        (%)          (%)      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

[[Page 4387]]

Table 1). The Scott Bar salamander has the smallest range, covering 
approximately 136,740 ac (55,335 ha), and occurs on the smallest 
proportion of Federal lands (78 percent) within the complex (see Table 
1).
    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 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.
    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. 
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.
    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.

[[Page 4388]]



  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
----------------------------------------------------------------------------------------------------------------
                                                                                     Scott Bar        SMS-SBS
                                                   Applegate SMS    Grider SMS    salamander \1\      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.

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 
impleme