On the north slope of southwest Montana’s Gravelly Mountains, nestled among sub-alpine meadows and timbered slopes, are the scenic Axolotl Lakes. Their unusual name comes from an unusual inhabitant: the neotonic form of the tiger salamander (Ambystoma tigrinum). Commonly called "axolotl," this form of the salamander retains its juvenile traits into maturity.

Montana’s axolotls, however, are not true axolotls. That honor goes to a distantly related species (Ambystoma mexicanum) occurring only in Lake Xochimilco in central Mexico. But they do exhibit nearly all that salamander’s famous trails: a fully aquatic lifestyle, retention of gills into sexual maturity, limb regeneration, and a finlike tail.  The major difference between a true axolotl and Montana's axolotl is that Montana's will readily morph into a terrestrial tiger salamander if its environmental conditions improve.  However, it is extremely rare to find the Mexican species in the wild in other than the neotenic form.

The name axolotl comes from the Aztec language. One of the most popular translations of the name connects the axolotl to the god of deformations and death, Xolotl.  The most commonly accepted translation is "water-dog" (from "atl" for water, and "xolotl," which can also mean dog).

The axolotls that inhabit the Axolotl Lakes are actually the neotonic form of the blotched tiger salamander (Ambystoma tigrinum melanostictum).   These creatures can reach 12 inches at full growth, with smaller 6- to 10-inch specimens the most common. Within some populations are two distinct foraging lifestyles. The most common form feeds on insect larvae and small crustaceans such as scuds. The second has a much more sinister side in its feeding preferences. This form is cannibalistic — a large percentage of its diet consists of its brethren. Its larger head and mouth full of sharp teeth assists it in this pursuit.

Scientists don’t know much about axolotls in Montana or elsewhere.  How long they can survive in the wild remains a mystery. However, some from the Mexican species have lived for 20 years and more in captivity.

Why don’t these unusual creatures turn into adults? Several conditions contribute to this trait: high altitude, cold water temperature, lack of predation in the water, dry conditions outside the water and hormones.

During the summer of 2007, fisheries biologist Paul Hutchinson and Bureau of Land Management volunteer Kyler Morse conducted an axolotl survey in the Axolotl Lakes chain to determine their distribution. During three days of survey, they found axolotls in only two lakes.  Hutchinson and Morse caught and measured several dozen axolotls, with several individuals measuring more than 10 inches.  They also observed but did not capture larger axolotls, which they estimated to have exceeded 11 inches.

Historically, axolotls may have occurred in all of the natural lakes in the Axolotl area.  Today they are only found in two.  Introductions of trout into several of the lakes around the turn of the century likely wiped out other populations.

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