Dicamptodon aterrimus - (Cope, 1868 "1867")
Idaho Giant Salamander
Taxonomic Status: Accepted
Related ITIS Name(s): Dicamptodon aterrimus (Cope, 1868) (TSN 173741)
Unique Identifier: ELEMENT_GLOBAL.2.104014
Element Code: AAAAH01030
Informal Taxonomy: Animals, Vertebrates - Amphibians - Salamanders
 
Kingdom Phylum Class Order Family Genus
Animalia Craniata Amphibia Caudata Dicamptodontidae Dicamptodon
Genus Size: B - Very small genus (2-5 species)
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Concept Reference
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Concept Reference: Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.
Concept Reference Code: B85FRO01HQUS
Name Used in Concept Reference: Dicamptodon aterrimus
Taxonomic Comments: Good (1989) examined genetic relationships and concluded that the genus Dicamptodon comprises 4 species: D. ensatus (west-central California), D. aterrimus (Rocky Mountains of Idaho and adjacent Montana; see also Daugherty et al. (1983), D. tenebrosus (southern British Columbia to northern California), and D. copei (Washington and northern Oregon). A previous study of morphological variation (Nussbaum 1976) concluded that Dicamptodon includes only 2 species, copei and ensatus (the latter including aterrimus and tenebrosus).
Conservation Status
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NatureServe Status

Global Status: G3G4
Global Status Last Reviewed: 13May2013
Global Status Last Changed: 13May2013
Ranking Methodology Used: Ranked by calculator
Rounded Global Status: G3 - Vulnerable
Reasons: Small range in Idaho and a small area in adjacent Montana; recent trend uncertain but probably relatively stable or slowly declining; negatively affected in some areas by habitat loss, fragmentation, and degradation due to logging, road construction, and other factors; climate change is a potential threat.
Nation: United States
National Status: N3N4 (13May2013)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Idaho (S4), Montana (S2)

Other Statuses

IUCN Red List Category: LC - Least concern

NatureServe Global Conservation Status Factors

Range Extent: 20,000-200,000 square km (about 8000-80,000 square miles)
Range Extent Comments: Range includes northern Idaho and a small adjoining portion of extreme western Montana, from the South Fork of the Salmon River to the St. Regis drainage in Montana (Nussbaum et al. 1983, Petranka 1998, Werner et al. 2004, Mullen et al. 2010). Elevational range extends to at least 2,135 meters.

Area of Occupancy: 126-2,500 4-km2 grid cells
Area of Occupancy Comments: This species occurs in over 400 kilometers (250 miles) of stream (C. Peterson, pers. comm., 1997).

Number of Occurrences: 81 - 300
Number of Occurrences Comments: The number of distinct occurrences has not been determined using standardized criteria, but this species is represented by a large number of occurrences and locations (as defined by IUCN). Species is extant in probably more than 100 locations; historical distribution is poorly documented (C. Peterson, pers. comm., 1997). Sepulveda and Lowe (2009) found this species in 18 of 40 sampled headwater streams in the Lochsa River basin, Idaho.

Population Size: 10,000 - 100,000 individuals
Population Size Comments: Total adult population size is unknown but may exceed 10,000. This species is still locally abundant in forested headwater streams (Lohman and Bury 2005). Adults are cryptic and relatively difficult to detect, whereas larvae are easy to find (Sepulveda and Lowe 2009).

Overall Threat Impact: Medium
Overall Threat Impact Comments: Primary threat is loss, degradation, and particularly fragmentation of habitat resulting from logging, road construction, and other factors (Fisher 1989, Hossack 1998, Lohman and Bury 2005). Habitat fragmentation interferes with natural metapopulation dynamics (Sepulveda and Lowe 2009, Mullen et al. 2010). Sepulveda and Lowe (2009) found that the probability of occurrence of this species was highest in unfragmented headwater drainages with few roads; they also found that this species was numerous in streams with a high proportion of embedded substrate and fine sediments, indicating that sedimentation is not necessarily a significant threat. Historical placer mining probably negatively affected some populations.

This species readily recolonizes disturbed areas as they recover or are restored. Genetic structure of populations suggests that such recolonization is most likely to occur within catchments (Mullen et al. 2010).

Climate change is a potential threat; habitat could be lost or rendered less suitable as a result of drought or increased temperatures.

Short-term Trend: Decline of <30% to relatively stable
Short-term Trend Comments: Trend over the past 10 years or three generations is uncertain, but area of occupancy and abundance probably have been relatively stable or slowly declining. In the late 1990s, this species was regarded as stable in undisturbed areas, and it was recolonizing disturbed areas as they improved (C. Peterson, pers. comm., 1997).

Long-term Trend: Decline of <50% to Relatively Stable
Long-term Trend Comments: Long-term trend is uncertain, but area of occupancy and abundance likely have declined (Lohman and Bury 2005), but the degree of decline is unknown. Overall range extent has not declined very much if at all (Lohman and Bury 2005).

Intrinsic Vulnerability: Moderately vulnerable

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Other NatureServe Conservation Status Information

Distribution
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Global Range: (20,000-200,000 square km (about 8000-80,000 square miles)) Range includes northern Idaho and a small adjoining portion of extreme western Montana, from the South Fork of the Salmon River to the St. Regis drainage in Montana (Nussbaum et al. 1983, Petranka 1998, Werner et al. 2004, Mullen et al. 2010). Elevational range extends to at least 2,135 meters.

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
Endemism: endemic to a single nation

U.S. & Canada State/Province Distribution
United States ID, MT

Range Map
Note: Range depicted for New World only. The scale of the maps may cause narrow coastal ranges or ranges on small islands not to appear. Not all vagrant or small disjunct occurrences are depicted. For migratory birds, some individuals occur outside of the passage migrant range depicted. For information on how to obtain shapefiles of species ranges see our Species Mapping pages at www.natureserve.org/conservation-tools/data-maps-tools.

Range Map Compilers: IUCN, Conservation International, NatureServe, and collaborators, 2004


U.S. Distribution by County Help
State County Name (FIPS Code)
ID Adams (16003), Benewah (16009), Clearwater (16035), Idaho (16049), Latah (16057), Nez Perce (16069), Shoshone (16079), Valley (16085)
MT Mineral (30061)
* Extirpated/possibly extirpated
U.S. Distribution by Watershed Help
Watershed Region Help Watershed Name (Watershed Code)
17 Middle Clark Fork (17010204)+, Upper Coeur D'alene (17010301)+, South Fork Coeur D'alene (17010302)+, St. Joe (17010304)+, Hangman (17010306)+, North Fork Payette (17050123)+, Weiser (17050124)+, Palouse (17060108)+, Middle Salmon-Chamberlain (17060207)+, South Fork Salmon (17060208)+, Lower Salmon (17060209)+, Little Salmon (17060210)+, Lower Selway (17060302)+, Lochsa (17060303)+, South Fork Clearwater (17060305)+, Clearwater (17060306)+, Upper North Fork Clearwater (17060307)+, Lower North Fork Clearwater (17060308)+
+ Natural heritage record(s) exist for this watershed
* Extirpated/possibly extirpated
Ecology & Life History
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Basic Description: A large salamander (highly aquatic).
Reproduction Comments: Breeding occurs in both spring and fall. Adult females deposit a clutch of about 135-200 eggs in spring. Females attend eggs until hatching. Larvae metamorphose usually in 18-24 months but sometimes attain sexual maturity in the larval form (Nussbaum et al. 1983, Stebbins 2003).
Ecology Comments: Individuals attain sexual maturity in both larval and terrestrial forms at sizes exceeding 115 mm SVL (Nussbaum et al. 1983).
Non-Migrant: N
Locally Migrant: Y
Long Distance Migrant: N
Mobility and Migration Comments: Adults migrate locally between aquatic breeding sites and terrestrial nonbreeding habitats.
Riverine Habitat(s): CREEK, MEDIUM RIVER, Moderate gradient, Pool, SPRING/SPRING BROOK
Lacustrine Habitat(s): Shallow water
Palustrine Habitat(s): Riparian
Terrestrial Habitat(s): Forest - Conifer
Special Habitat Factors: Benthic, Burrowing in or using soil, Fallen log/debris
Habitat Comments: Metamorphosed adults inhabit humid forests and may be found under rocks, logs, or bark near mountain streams or rocky shores of mountain lakes (Stebbins 2003). Egg deposition sites are in water-filled chambers or crevices under or among logs or rocks. Larvae usually inhabit clear, cold mountain streams, sometimes mountain lakes and ponds.

Sepulveda and Lowe (2009) found that probability of D. aterrimus occurrence was highest in roadless drainages and lowest in spatially isolated streams and in drainages with high old-growth forest density. They determined that D. aterrimus density was greatest in streams with a high proportion of embedded substrate and fine sediment, which possibly reflected adaptation to a high frequency of natural disturbances, such as landslides, in the study area. In general, D. aterrimus is tolerant of a wide range of local conditions within streams (Sepulveda and Lowe 2009).

Adult Food Habits: Carnivore, Invertivore
Immature Food Habits: Carnivore, Invertivore
Food Comments: Larvae feed on a wide variety of aquatic invertebrates as well as some small vertebrates (e.g., fishes, tadpoles, other larval salamanders). Adults eat terrestrial invertebrates, also small snakes, shrews, mice, salamanders, etc.
Adult Phenology: Circadian, Hibernates/aestivates
Immature Phenology: Circadian, Hibernates/aestivates
Length: 30 centimeters
Economic Attributes Not yet assessed
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Management Summary
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Stewardship Overview: Sepulveda and Lowe (2009) suggested that "management and conservation efforts for this species focus on protecting roadless areas and restoring stream connectivity in human-impacted areas, rather than on only improving habitat quality within streams."
Population/Occurrence Delineation
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Group Name: Dicamptodontid (Pacific Giant) Salamanders

Use Class: Not applicable
Minimum Criteria for an Occurrence: Occurrences are based on evidence of historical presence, or current and likely recurring presence, at a given location. Such evidence minimally includes collection or reliable observation and documentation of one or more individuals (including larvae or eggs) in or near appropriate habitat where the species is presumed to be established and breeding.
Separation Barriers: Heavily traveled road, such that salamanders almost never successfully traverse the road; road with a barrier that is impermeable to salamanders; large impoundment or lake containing predatory fishes; areas of intensive development dominated by buildings and pavement.
Separation Distance for Unsuitable Habitat: 1 km
Separation Distance for Suitable Habitat: 5 km
Separation Justification: Metamorphosed adults readily traverse natural and seminatural upland habitats during wet weather. McComb et al. (1993) found that adult D. tenebrosus typically are within 50 m of a stream but sometimes range up to 400 m away. Radio-tracked D. tenebrosus traveled up to 305 m from their capture site between July and October (Johnston 1998). Other Dicamptodon (except aquatic D. copei) likely behave similarly. D. copei is very rarely found in the metamorphosed stage and is unlikely to travel more than a few feet from a stream or lake edge (Corkran and Thoms 1996, Nussbaum 1983).

Ferguson (1998) found that larvae are relatively sedentary, with the majority of individuals moving less than 50 m between July and October. Based on patterns of recolonization of small (25-40 m) zones from which larvae were removed, local reproduction appeared to be a more effective mechanism of repopulating an area than larval immigration (Ferguson 2000). Full population recovery occurred within one year in one of four depopulated sites; data indicated that recolonization of a 400-m-long stream segment, such as might be depopulated as a result of logging, could take 8-55 years based on documented dispersal rates (optimistically assuming no decline in habitat suitability) (Ferguson 2000). However, Ferguson's larval study encompassed only about 15 months whereas the time frame for effective dispersal of these long-lived salamanders should be several years. Also, periodic flooding seemingly would facilitate long-distance dispersal of larvae, and adult movements (which might encompass several hundred meters annually) likely promote siginificant upstream dispersal.

Although dispersal appears to be somewhat slow, it is likely that occupied sites within several kilometers of each other and joined by suitable habitat are part of the same population.

Inferred Minimum Extent of Habitat Use (when actual extent is unknown): .5 km
Date: 21Sep2004
Author: Hammerson, G.
Population/Occurrence Viability
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U.S. Invasive Species Impact Rank (I-Rank) Not yet assessed
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Authors/Contributors
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NatureServe Conservation Status Factors Edition Date: 13May2013
NatureServe Conservation Status Factors Author: Hammerson, G.
Element Ecology & Life History Edition Date: 13May2013
Element Ecology & Life History Author(s): Hammerson, G.

Zoological data developed by NatureServe and its network of natural heritage programs (see Local Programs) and other contributors and cooperators (see Sources).

References
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  • Anderson, J.D. 1968. Dicamptodon, D. ensatus. Catalogue of American Amphibians and Reptiles. 76:1-2.

  • Behler, J. L., and F. W. King. 1979. The Audubon Society field guide to North American reptiles and amphibians. Alfred A. Knopf, New York. 719 pp.

  • Blackburn, L., P. Nanjappa, and M. J. Lannoo. 2001. An Atlas of the Distribution of U.S. Amphibians. Copyright, Ball State University, Muncie, Indiana, USA.

  • Daugherty, C. H., F. W. Allendorf, W. W. Dunlap and K. L. Knudsen. 1983. Systematic implications of geographic patterns of genetic variation in the genus DICAMPTODON. Copeia 1983:679-691.

  • Daugherty, C.H., F.W. Allendorf, W.W. Dunlap and K.L. Knudsen. 1983. Systematic implications of geographic patterns of genetic variation in the genus Dicamptodon. Copeia 1983:679-691.

  • Fisher, T. R. 1989. Application and testing of indices of biotic integrity in northern and central Idaho headwater streams. Master's thesis. University of Idaho, Moscow, Idaho.

  • Frost, D. R. 1985. Amphibian species of the world. A taxonomic and geographical reference. Allen Press, Inc., and The Association of Systematics Collections, Lawrence, Kansas. v + 732 pp.

  • Good, D. A. 1989. Hybridization and cryptic species in DICAMPTODON (Caudata: Dicamptodontidae). Evolution 43:728-744.

  • Good, D. A. 1989. Hybridization and cryptic species in DICAMPTODON (Caudata: Dicamptodontidae). Evolution 43:728-744.

  • Hossack, B. R. 1998. Landscape influences on headwater streams and stream amphibians in northern Idaho. Master's thesis. University of Idaho, Moscow, Idaho.

  • Jones, L.L.C., W. P. Leonard, and D. H. Olson, editors. 2005. Amphibians of the Pacific Northwest. Seattle Audubon Society, Seattle, Washington. xii + 227 pp.

  • Lohman, K., and R. B. Bury. 2005. Dicamptodon aterrimus (Cope, 1867). Idaho giant salamander. Pages 651-652 in M.. Lannoo, editor. Amphibians declines: the conservation status of United States species. University of California Press, Berkeley.

  • Mullen, L. B., H. A. Woods, M. K. Schwartz, A. J. Sepulveda, and W. H. Lowe. 2010. Scale-dependent genetic structure of the Idaho giant salamander (Dicamptodon aterrimus) in stream networks. Molecular Ecology 19:898-909.

  • Nussbaum, R. A. 1976. Geographic variation and systematics of salamanders of the genus DICAMPTODON Strauch (Ambystomatidae). Univ. Michigan Mus. Zool. Misc. Publ. 149:1-94.

  • Nussbaum, R.A. 1969. Nests and eggs of the Pacific giant salamander, Dicamptodon ensatus (Escholtz). Herpetologica 25(4):257-262.

  • Nussbaum, R.A. 1976. Geographic variation and systematics of salamanders of the genus Dicamptodon Strauch (Ambysomatidae). Misc. Publ. Mus. Zool. Univ. Michigan 149:1-94.

  • Nussbaum, R.A. and G.R. Clothier. 1973. Population structure, growth, and size of larval Dicamptodon ensatus (Erscholtz). Northwest Science 47(4):218-227.

  • Nussbaum, R.A., E.D. Brodie, Jr., and R.M. Storm. 1983. Amphibians and Reptiles of the Pacific Northwest. University Press of Idaho, Moscow, Idaho. 332 pp.

  • Petranka, J. W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington, D.C.

  • Reichel, J.D., and D. Flath. 1995. Identification of Montana's amphibians and reptiles. Montana Outdoors 26(3):15-34.

  • Sepulveda, A. J., and W. H. Lowe. 2009. Local and landscape-scale influences on the occurrence and density of Dicamptodon aterrimus, the Idaho giant salamander. Journal of Herpetology 43:469-484.

  • Stebbins, R. C. 1985a. A field guide to western reptiles and amphibians. Second edition. Houghton Mifflin Company, Boston, Massachusetts. xiv + 336 pp.

  • Werner, J. K., B. A. Maxell, P. Hendricks, and D. L. Flath. 2004. Amphibians and reptiles of Montana. Mountain Press Publishing Company, Missoula, Montana. xii + 262 pp.

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