It is the most sexually dichromatic species of anuran in North America, with males and females displaying strikingly divergent patterns and coloration at maturity.

As juvenile males mature, their black blotches shrink and ultimately disappear, whereas they expand and reticulate in developing females.

[7] Charles Camp chose the specific epithet "canorus" (meaning tuneful) for the species based on its advertisement call.

[8][13] Until then, juveniles resemble adult females: they have a background color varying from brown to grey with generally unconnected black blotches encircling the warts.

Unlike adult females, juveniles have a thin mid-dorsal stripe that is white or cream-colored, and orange tubercles on the undersides of their hands and feet.

Depending on the population density they will either join a breeding chorus by making an advertisement call to females, or will actively search for them.

[18][19] More specifically, breeding takes place in shallow snowmelt ponds or flooded areas, and eggs are usually deposited in water less than 5 cm deep.

[7][8] Shallow water makes eggs vulnerable to freezing, because nighttime temperatures are particularly low during springtime snow melt off.

[7] Time from hatching to tadpole metamorphosis is 4–6 weeks, and this is highly dependent upon environmental factors (elevation, weather, food, competition) and possibly genetic background.

Metamorphs appear to move away from breeding ponds soon after transformation, however they probably overwinter nearby in stream channels and associated vegetation (willows, sedges, and grasses).

Adult upland foraging habitat tends to be covered in seeps and springs, willows, tall forbs, granitic boulders, or (at lower elevation) forest clearings.

[20][18] Rodent burrows play an essential role in providing shelter from predation and weather, as do willows, logs, and rocks.

[17][7][8][20][18] Overwintering habitat is also includes the burrows of rodents such as pocket gophers, voles, and Belding's ground squirrels, along with willow root tangles, which all probably keep an optimal thermal and mesic environmental for hibernating toads.

[6] Overwintering sites are rodent burrows or willow thickets (see "Habitat Utilization"), and the first freezing nighttime temperatures seem to cue adult toads to seek hibernacula.

They lunge at prey and open their mandibles, causing their sticky tongue to unfold, flip downward, and pull the animal into their mouths.

[7] Males spend disproportionately more time in shallow, brown, silty breeding ponds, where they are highly exposed to predators.

Karlstrom[7] was the first to hypothesize, based on the distribution of A. canorus in Yosemite National Park, that glaciers had helped the species differentiate from A. boreas.

Recent work has showed this is likely true, and part of a larger pattern of glacial action bifurcating the species into new lineages.

[26] The species likely originated in the early Pleistocene, and many of the glacial cycles since then have isolated toads into western and eastern refugia; here they have adapted to different climatic conditions, reinforcing the formation of new lineages.

Although threats to persistence of the species are less understood than in other California amphibians such as the Sierra Nevada yellow-legged frog, the two most significant appear to be drought (increasing with climate change) and disease (primarily chytridiomycosis).

[16] A. boreas A. nelsoni A. exsul A. canorus *** A. punctatus A. quercicus A. kelloggi A. debilis A. retiformis A. speciosus A. cognatus A. californicus A. microscaphus A. americanus A. baxteri A. fowleri A. hemiophrys A. houstonensis A. terrestris A. velatus A. woodhousii