Idaho Giant Salamander (Dicamptodon aterrimus) 



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

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

 3.5 to 8". 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 

 fin 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. 



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. 

 As discussed for tiger salamanders, 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 stream and 

 moving logs, rocks, or other hiding places just upstream 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, but they are 

 regularly found in Idaho just over the Mineral County line. Two unverified sight records 

 exist from Gilt Edge Creek and Big Creek in Mineral County. 



Montana Natural Heritage Program rank: G4 S 1 ? 



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