Cope's Giant Salamander
© 2016 William Flaxington (1 of 19)
Dicamptodon copei Nussbaum, 1970
Lawrence L.C. Jones1
1. Historical versus Current Distribution. Cope's giant salamanders (Dicamptodon copei) are known from western Washington and extreme northwestern Oregon (Nussbaum, 1970, 1976, 1983; Jones and Aubry, 1984; McAllister, 1995; Leonard et al., 1998). In Washington, they are known from the Cascades (south of Mt. Rainier), Willapa Hills, and Olympic Peninsula (except for most of the northeast portion; R.B.B., unpublished data). In Oregon, Cope's giant salamanders are confined to the vicinity of the Columbia River Gorge (Cascades and Coast Range). They can be locally abundant and are widely distributed through much of their range, but tend to have a more spotty distribution where they are sympatric with Pacific giant salamanders (D. tenebrosus). Although it is likely that development and deforestation may have resulted in reduction in some populations, there has been no apparent reduction in range.
2. Historical versus Current Abundance. Little is known about the effects of timber harvest on Cope's giant salamanders. Ruggiero et al. (1991) state that this species is associated with old‑growth forests and/or stands with similar structural attributes. However, Bury et al. (1991) found densities somewhat lower in old forests than in young, naturally regenerated forest streams in the Washington Cascades. Unfortunately, results of investigations on this species may be obscured by combining Cope's giant salamander and Pacific giant salamander data sets, as these species are phenotypically similar when young (e.g., Antonelli et al., 1972; Wilkins and Peterson, 2000). Ongoing investigations in the Olympic Peninsula and elsewhere will help clarify habitat relationships.
3. Life History Features.
i. Breeding migrations. Unknown.
ii. Breeding habitat. Likely to be the same as egg deposition sites, which include hidden chambers under rocks and logs and in cutbanks (Nussbaum et al., 1983; Steele et al., 2003).
i. Egg deposition sites. Nussbaum et al. (1983) reported on nine nests found in nature. Eggs are deposited in spring–fall. Females placed their eggs in hidden chambers under rocks and logs and in cutbanks. Steele et al. (2003) recently reported on two clutches.
ii. Clutch size. Clutches range from 25–115 eggs, averaging about 50. Females guard the eggs, and conspecifics are often found with bite marks, which suggests nest defense. The two nests discovered by Steele et al. (2003) contained 23 and 28 eggs.
i. Length of larval stage. In general, the species is larviform throughout its life and growth rates are unknown.
ii. Larval requirements.
a. Food. Antonelli et al. (1972) studied food habits of Cope’s giant salamanders and Pacific giant salamanders, but did not distinguish between the two species or age classes, except transformed individuals were not included. They considered Cope’s giant salamanders to be opportunistic, feeding primarily on invertebrate stream benthos.
b. Cover. Bury et al. (1991) found that Cope’s giant salamanders (paedomorphic animals and larvae combined) primarily inhabited pools in mountain streams, using large stones for cover.
iii. Larval polymorphisms. None.
iv. Features of metamorphosis. Metamorphosis in Cope’s giant salamanders is extremely rare. To date, six naturally metamorphosed individuals have been reported in the literature (Nussbaum, 1983; Jones and Corn, 1989; Loafman and Jones, 1996). All were from the Olympic Peninsula, except one from the Washington Cascades. All are extremely similar in coloration and external morphology (see color photograph in Jones and Corn, 1989), although we did not examine the Cascades specimen. This species has little proclivity for metamorphosis, as demonstrated by intensive thyroxin treatment to induce transformation (Nussbaum, 1976).
v. Post‑metamorphic migrations. Unknown, but transformed individuals were usually found near streams.
vi. Neoteny. This species appears to be a near-obligate paedomorphic species.
D. Juvenile Habitat. Not applicable.
E. Adult Habitat. Unknown for metamorphosed individuals and little studied for larviform adults. Paedomorphic adults and larvae are usually associated with pools in small–moderately sized rocky mountain streams and, occasionally, montane lakes (Nussbaum et al., 1983; Bury et al., 1991).
F. Home Range Size. Unknown.
G. Territories. Unknown, but individuals often have scars inflicted by conspecifics (Nussbaum et al., 1983), which may be due to nest protection, territoriality, or both.
H. Aestivation/Avoiding Dessication. Surface activity is normally high during the summer (Antonelli et al., 1972), but individuals probably seek refuge during dessicating conditions.
I. Seasonal Migrations. Unknown.
J. Torpor (Hibernation). Surface activity is absent or reduced in the winter, at least in areas where temperatures are near freezing (Antonelli et al., 1972).
K. Interspecific Associations/Exclusions. They are sympatric with Pacific giant salamanders, except on the Olympic Peninsula, where Cope’s giant salamanders are the only members of the genus. Nussbaum (1976) listed eight sites where these two species coexist. They are not known to hybridize (Nussbaum, 1976; Good, 1989). Recent studies have yielded little information on the extent or mechanism of co-existence or interactions of sympatric giant salamanders. Torrent salamanders (Rhyacotriton spp., including Olympic torrent salamanders [R. olympicus], Columbia torrent salamanders [R. kezeri], and Cascade torrent salamanders [R. cascadae]), and tailed frogs (Ascaphus truei) often co‑occur with Cope’s giant salamanders. In wet edge habitat, Van Dyke's salamanders (Plethodon vandykei) may occur throughout its Washington range and Dunn's salamanders (P. dunni) in its Oregon and southwestern Washington range.
L. Age/Size at Reproductive Maturity. From 65–77 mm SVL (Nussbaum, 1976).
M. Longevity. Unknown.
N. Feeding Behavior. Branchiate adults may feed on larger prey, including tailed frog larvae and juveniles, small fish, and smaller congeners or their eggs (Antonelli et al., 1972; Kaplan and Sherman, 1980; Nussbaum et al., 1983; Jones and Raphael, 1998). They generally feed in streams, but sometimes venture out of the stream in wet weather (Nussbaum et al., 1983). Diet for metamorphosed forms is unknown.
O. Predators. Cope’s giant salamanders, Pacific giant salamanders, common garter snakes (Thamnophis sirtalis), and water shrews (Sorex palustris) have been reported (Nussbaum et al., 1983; Loafman and Jones, 1996).
P. Anti-Predator Mechanisms. Unreported, but flight is evident (personal observations).
Q. Diseases. Unknown.
R. Parasites. Unknown.
4. Conservation. There has been no apparent reduction in the range of Cope’s giant salamanders. They are widely distributed through much of their range and can be locally abundant. While little is known about the effects of timber harvesting on Cope's giant salamanders, it is likely that development and deforestation may have resulted in the reduction of some populations. According to Levell (1997), Cope's giant salamanders are listed as Protected in Oregon.
1Lawrence L.C. Jones
2R. Bruce Bury
Literature references for Amphibian Declines: The Conservation Status of United States Species, edited by Michael Lannoo, are here.
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