Analysis of fossil records, genetics, and biogeography suggest A. macrodactylum and A. laterale are descended from a common ancestor that gained access to the western Cordillera with the loss of the mid-continental seaway toward the Paleocene.

The long-toed salamander hibernates during the cold winter months, surviving on energy reserves stored in the skin and tail.

[8][9] The following biogeographic interpretation on the origins of A. macrodactylum into western North America is based on a descriptive account of fossils, genetics, and biogeography.

[13] A scenario for the splitting of A. macrodacylum and other western temperate species from their eastern counterparts involves Rocky Mountain uplift in the late Oligocene into the Miocene.

The orogeny created a climatic barrier by removing moisture from the westerly air stream and dried the midcontinental area, from southern Alberta to the Gulf of Mexico.

Mesic forests were established in western North America by the mid Eocene and attained their contemporary range distributions by the early Pliocene.

The temperate forest valleys and montane environments of these time periods (Paleogene to Neogene) would have provided the physiographic and ecological features supporting analogs of contemporary Ambystoma macrodactylum habitats.

The rise of the Cascades causing the xerification of the Columbia Basin is a major biogeographic feature of western North America that divided many species, including A. macrodactylum, into coastal and inland lineages.

[11][22] The breeding fidelity of long-toed salamanders (philopatry) and other migratory behaviours reduce rates of dispersal among regions, such as within mountain basins.

[23] Natural breaks in the range of dispersal and migration occur where ecosystems grade into drier xeric low-lands (such as prairie climates) and at frozen or harsher terrain at high elevation extremes (2,200 meters (7,200 ft)).

[24] Thompson and Russell found another evolutionary lineage that originates in a glacially restricted area of the Salmon River Mountains, Idaho.

[11] With the arrival of the Holocene interglacial, approximately 10,000 years ago, the Pleistocene glaciers receded and opened a migratory path linking these southern populations to northern areas where they currently overlap with A. m. krausei and co-migrated north into the Peace River (Canada) Valley.

[11] Ferguson also noted an intergradation in the same geographic area, but between the morphological subspecies A. m. columbianum and A. m. krausei that run parallel to the Bitterroot and Selkirk ranges.

[26][20] The long-toed salamander is an ecologically versatile species living in a variety of habitats, ranging from temperate rainforests, coniferous forests, montane riparian, sagebrush plains, red fir forest, semiarid sagebrush, cheatgrass plains, to alpine meadows along the rocky shores of mountain lakes.

[36] The distribution reconnects in northeastern Sierra Nevada running continuously along the Pacific Coast to Juneau, Alaska, with populations dotted along the Taku and Stikine River valleys.

In the northern extent of its range, the eggs are laid in lumpy masses along grass, sticks, rocks, or the mucky substrate of a calm pond.

[40] Females invest a significant amount of resources into egg production, with the ovaries accounting for over 50% of the body mass in the pre-breeding season.

[46] After the larvae grow and mature, for at least one season (the larval period lasts about four months on the Pacific coast),[37] they absorb their gills and metamorphose into terrestrial juveniles that roam the forest undergrowth.

[23] As adults, long-toed salamanders often go unnoticed because they live a subterranean lifestyle digging, migrating, and feeding on the invertebrates in forest soils, decaying logs, small rodent burrows or rock fissures.

[55] The timing of breeding can be highly variable; of notable mention, several egg masses in early stages of development were found on July 8, 1999 along the British Columbia provincial border outside Jasper, Alberta.

[56] Gender differences (or sexual dimorphism) in this species are only apparent during the breeding season, when mature males display an enlarged or bulbous vent area.

[57] Like other ambystomatid salamanders, they have evolved a characteristic courtship dance where they rub bodies and release pheromones from their chin gland prior to assuming a copulatory mating position.

Once in position, the male deposits a spermatophore, which is a gooey stalk tipped with a packet of sperm, and walks the female forward to be inseminated.

However, during the cold winter months in the northern parts of its range, the long-toed salamander burrows below the frost-line in a coarse substrate to hibernate in clusters of 8–14 individuals.

[62] When threatened, the long-toed salamander will wave its tail and secrete an adhesive white milky substance that is noxious and likely poisonous.

[62] Its skin colors and patterns are diverse, ranging from a dark black to reddish brown background that is spotted or blotched by a pale-reddish-brown, pale-green, to a bright yellow stripe.

Conservation priorities focus at the population level of diversity, which is declining at rates ten times that of species extinction.

[76] Places such as Waterton Lakes National Park have installed a road tunnel underpass to allow safe passage and to sustain the migration ecology of the species.

[2] The distribution of the long-toed salamander overlaps extensively with the forestry industry, a dominant resource supporting the economy of British Columbia and the western United States.

[82][83][84] The subspecies Ambystoma macrodactylum croceum (Santa Cruz Long-toed Salamander) is of particular concern and it was afforded protections in 1967 under the US Endangered Species Act.