Amphibians
Idaho Giant Salamander
Dicamptodon aterrimus · also called Idaho giant salamanders
Every other giant salamander in its genus lives along the Pacific coast. The Idaho giant salamander lives landlocked in the Rocky Mountains instead, hundreds of miles inland, a population left behind when a once-continuous range broke apart and the connecting habitat between coast and mountains quietly disappeared.
Overview
The Idaho giant salamander, Dicamptodon aterrimus, is a large, terrestrial-adult salamander restricted to cold mountain streams in the Rocky Mountains of central Idaho and adjacent Montana. Unlike its permanently aquatic relative Cope’s giant salamander, it typically completes full metamorphosis.
A relict stranded inland
Genetic and geographic evidence points to the Idaho giant salamander as a relict population, isolated from its coastal relatives when a once-continuous range fragmented, leaving this inland population to persist alone in the Rockies ever since.
Status
Near Threatened — its naturally restricted, isolated range combined with logging-related stream disturbance has raised ongoing conservation concern.
Idaho Giant Salamander: common questions
Why is the Idaho giant salamander found so far from its closest relatives?
The Idaho giant salamander's isolated range in the Rocky Mountains of central Idaho and adjacent Montana is generally understood to be a relict of a once broader, more continuous distribution shared with its coastal relatives, with the Idaho population left stranded inland as suitable connecting habitat disappeared over a long span of geological time, leaving it hundreds of miles from the coastal Pacific Northwest habitat its relatives occupy today.
Does the Idaho giant salamander stay aquatic like Cope's giant salamander?
No, unlike Cope's giant salamander, which rarely completes metamorphosis and mostly remains permanently aquatic, the Idaho giant salamander typically does transform into a terrestrial, lunged adult, following the more typical life cycle pattern also seen in its coastal and California giant salamander relatives.
Can an Idaho giant salamander actually make a sound?
Yes, when threatened or handled, an Idaho giant salamander is capable of producing a distinctive low, growling or barking vocalisation, an unusual ability among salamanders, most species of which are considered largely voiceless, making this vocal capability one of the more distinctive traits within its genus.
Why is the Idaho giant salamander considered Near Threatened?
The Idaho giant salamander already occupies a naturally restricted and isolated range within the Rocky Mountains of central Idaho and adjacent Montana, and this limited distribution, combined with ongoing pressures from logging-related habitat disturbance and changes to stream water quality, has contributed to its Near Threatened conservation status despite populations remaining more stable within protected forest watersheds.