Siskiyou Mountains salamander
© 2004 William Leonard (1 of 24)
Plethodon stormi Highton and Brame, 1965
R. Bruce Bury1
1. Historical versus Current Distribution. Siskiyou Mountains salamanders (Plethodon stormi) are restricted to the Siskiyou Mountains in the upper Klamath River, Siskiyou County, California, and the adjacent Applegate River watershed, Jackson and Josephine counties, Oregon (Brodie, 1970, 1971b; Highton and Larson, 1979; Bury, 1998; Bury and Pearl, 1999). Highton and Brame (1965) first described the species from five inland localities along the California–Oregon border. More recently, Siskiyou Mountains salamanders are known from 17 sites in Oregon and 10 in California (Bury, 1998). There are many new sites based on recent surveys (D. Clayton, R.B.B. and others; unpublished reports). The range of Siskiyou Mountains salamanders occupies an area of only about 35 x 75 km.
There is clinal variation in morphometric traits and color patterns of Del Norte salamanders (Plethodon elongatus) from coastal to inland areas, and in the Upper Klamath River they closely resemble populations of Siskiyou Mountains salamanders (Bury, 1973b). Siskiyou Mountains salamanders appear to be the inland terminus of Del Norte salamanders and likely became separated from more coastal groups during glacial times, evolving in isolation into a new species (Bury, 1998). Earlier, Stebbins (1985) recognized these as two subspecies (P. e. elongatus and P. e. stormi). However, Highton and Larson (1979), Leonard et al. (1993), Highton (1995b), and Petranka (1998) continue to recognize Siskiyou Mountains salamanders as a distinct species; a view supported by recent molecular genetics analyses (Mahoney, 2001).
Thompson Creek is a drainage of the Applegate River, Oregon, where Siskiyou Mountains salamanders occur on the east side of the valley and Del Norte salamanders are 2 km away on the west side. There is no indication of intergradation in this area. However, on the southern flanks of the Siskiyou Mountains in California, Siskiyou Mountains salamanders may intergrade with Del Norte salamanders (Bury, 1998). Several studies on the genetic variation of P. elongatus and P. stormi are underway (Mead et al., in review; M.J. Mahoney, unpublished data).
2. Historical versus Current Abundance. Siskiyou Mountains salamanders are listed as a Survey and Manage Species under the Northwest Forest Plan on federal lands, whereby ground‑disturbing activities are not permitted where the species occurs or within a 33 m buffer around suitable habitat (Clayton et al., in press). There has been considerable habitat loss and fragmentation due to past logging practices. This species, as with their sister species, Del Norte salamanders (P. elongatus; Welsh and Lind, 1995), is highly associated with rocky talus slopes in areas of dense mature and late-seral forest (Welsh and Lind, 1995; Bury, 1998; Ollivier et al., 2001). Once considered a Federal Candidate Species for listing, Siskiyou Mountains salamanders are recognized as a species of Special Concern by Oregon and California.
3. Life History Features.
A. Breeding. Reproduction is terrestrial.
i. Breeding migrations. Unknown.
ii. Breeding habitat. Unknown.
i. Egg deposition sites. Unknown; no nests are known from the wild. Eggs are likely deposited deep in rocky substrates.
ii. Clutch size. Average clutch size of dissected females was 9 eggs with a range of 2–18 (Nussbaum et al., 1983).
C. Direct Development. Females may stay with nests until eggs hatch.
D. Juvenile Habitat. Same as adults.
E. Adult Habitat. Salamanders of all sizes and sexes occur in talus and rocky soils or slopes and occasionally are found under logs, leaf litter, and other cover if talus is nearby (Nussbaum et al., 1983; Bury, 1998). Heavily wooded, north‑facing slopes with rocky talus contain the largest populations (Brodie, 1970; Nussbaum et al., 1983).
F. Home Range Size. Unknown, but related western red-backed salamanders (P. vehiculum) have a high site specificity, and mean distances between captures were 2.5 m for males and 1.7 m for females (Ovaska, 1988b). Similarly, the sibling species P. elongatus appears sedentary, rarely moving over 7.5 m2 in 3 yr (Welsh and Lind, 1992).
G. Territories. Unknown.
H. Aestivation/Avoiding Dessication. Salamanders are generally deep underground in dry summer conditions. During wet nights in summer, individuals may emerge from deeper locations to feed at the surface (Nussbaum et al., 1983).
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Inactive in cold winter months, but may appear on surface once soils warm above freezing.
K. Interspecific Associations/Exclusions. Co‑occur with ensatina salamanders (Ensatina eschscholtzii), clouded salamanders (Aneides ferreus), and black salamanders (A. flavipunctatus). No other species of Plethodon are known within the range of Siskiyou Mountains salamanders.
L. Age/Size at Reproductive Maturity. Mature males are 47–70 mm SVL, females are 56–70 mm SVL (Nussbaum et al., 1983).
M. Longevity. Unknown in the wild.
N. Feeding Behavior. Usually are sit‑and‑wait predators that dart out from cover to seize prey such as collembolans, termites, beetles, moths, spiders, and mites (Nussbaum et al., 1983).
O. Predators. None reported in literature, but likely are eaten by shrews, other carnivores, and garter snakes (Thamnophis sp.).
P. Anti-Predator Mechanisms. None reported.
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. In 1993, Siskiyou Mountains salamanders were placed on the Federal Survey and Manage species list, which was used for protecting Rare species under the Northwest Forest Plan. This status required surveying forest stands on federal lands before any proposed management activities and the protection of occupied sites with a 33-m or 1-tree-height (whichever is greater) protective buffer around suitable habitat where the species was detected. In June 2002, the status of the populations north of the crest of the Siskiyou Mountains (Applegate River drainage) was changed such that pre-project surveys are no longer required, but known sites are still supposed to be protected, as are any new sites that might be discovered serendipitously. South of the Siskiyou Mountain crest, pre-project surveys are still required. These changes were the result of new molecular genetics data indicating highly homogeneous populations north, and highly differentiated, as well as more geographically scattered, populations south, of the Siskiyou Mountain crest (Mead et al., in review). Mead et al. (in review) distinguish two lineages south of the Siskiyou Mountain crest that are distinct from the Applegate River drainage populations, with the southeasternmost populations (Scott Bar Mountain area of the Upper Klamath River) representing a lineage that is ancestral to all other P. stormi plus P. elongatus. Discovery and recognition of these new species will be of high conservation concern because they appear to occupy relatively small geographic pockets and occur in areas with resource extraction, primarily timber harvesting.
1R. Bruce Bury
2Hartwell H. Welsh Jr.
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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Citation: AmphibiaWeb. 2020. <http://amphibiaweb.org> University of California, Berkeley, CA, USA. Accessed 20 Sep 2020.
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