Species Potentially Present on the Bitterroot National Forest 



Idaho Giant Salamander {Dicamptodon aterrimus, formerly part of D. ensatus) 



Description: Adults have light tan or bronze marbling on a dark brown or black backgroimd. 

 The adult is heavy-bodied, with a large head and muscular legs; snout-vent lengths vary from 

 8-20 cm. Like all salamanders, it has smooth moist skin without scales. Adult Idaho Giant 

 Salamanders can be distinguished from other Montana species by a combination of 1 ) large 

 size and muscular legs; 2) marbled pattern; and 3) lack of a tubercle on the hind feet. Larval 

 Idaho Giant Salamanders are identified by their short, bushy, external gills, large size, dorsal 

 fm starting at or behind the rear limbs, and stream dwelling habitat. In contrast, other larval 

 salamanders found in Montana live in ponds, have long, feathery gills, and have a dorsal fin 

 originating far forward of the rear legs. This species was formerly the Northern Rocky 

 Mountain form of the Pacific Giant Salamander (see Nussbaum et al. 1983). 



Habitat and Habits: Transformed adults are seldom seen, but live in moist coniferous forests. 

 They may be found under logs, bark, or rocks, and are seen most often moving about on 

 warm rainy nights. Larval Idaho Giant Salamanders are found in swift, cold mountain 

 streams but may occasionally be found in lakes or ponds. Little is known about their 

 reproduction; Idaho Giant Salamanders may become sexually mature and breed while still 

 retaining external gills. 



Surveying: Larvae can be seen in pools or slow-water of streams at night and can be sampled 

 with a dipnet. During the day, larvae may be captured by putting a net across a sfream and 

 moving logs, rocks, or other hiding places just upsfream from it. Adults may occasionally be 

 found in and under logs on the forest floor. Since they move around at night, particularly 

 when it is warm and rainy they may be captured by either night searches or pitfall traps. 



Status: Idaho Giant Salamanders are not known with certainty in western Montana (two 



unverified sight records exist from Gilt Edge Creek and Big Creek in Mineral County), but 

 they are found on the Idaho side of the Bitterroot Mountains in Idaho County (Nussbaum et 

 al. 1983). Higher mountain streams, ponds and lakes along the Bitterroot Mountains Divide 

 should be searched for this species; if encountered, voucher specimens should be collected 

 and all observations should be thoroughly documented, reported to the Heritage Program, and 

 kept on file. 



Montana Natural Heritage Program rank: G4S1? 



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