Canadian Toad Anaxyrus hemiophrys

Family: Bufonidae

General Adult Description: Overall, Canadian Toads are similar in appearance with American Toads. Both these toads have a background color that is various shades of tan or brown. The back is covered in small to medium sized dark spots that typically contain one or two large warts per spot. The underside is mottled with black spots. A narrow white or pale line runs down the middle of the back. Unlike the American Toad, cranial crests on Canadian Toads are rarely present posterior to the eye and are fused together between the eyes to form a raised, bony boss. Parotoid glands are can still be kidney-shaped, but often are a bit rounder in appearance and are not in contact with cranial crests. Adult males have nuptial pads (dark, keratinized pads) on the first and second digits of the forearms that are used to help grasp the female during amplexus (breeding); females lack these pads. This species can be easily identified from other South Dakota toads by: 1) having a mottled underside (Woodhouse’s Toads and Great Plains Toads have white undersides) and 2) the presence of a boss between the eyes (American Toads lack a boss and have cranial crests posterior to the eye).

General Larval Description: Larval Canadian Toads can be difficult to distinguish from tadpoles of other species of true toads (Bufonidae). Tadpoles are small, black, and may be covered in small metallic gold flecks. The tail fin is clear and rounded at the tip.

Call Description: Male Canadian Toads have a trill lasting from 3–6 seconds in length. The call of American Toads is similar but often described as being more musical, less harsh, and longer in duration (5–30 seconds). Because this species may hybridize with American Toads, hybrids may have call characteristics intermediate of both species.

Behavior: The American Toad is primarily nocturnal and is a generalist predator that consumes a variety of insects and small invertebrates. Like most toads, Canadian Toads have spades that allow them to be proficient at digging into the substrate to bury themselves. During winter, all toads bury themselves (or use existing rodent burrows) below the frost line to avoid freezing temperatures.

Reproduction: This species breeds from late May to June and typically arrives at wetlands after Boreal Chorus Frogs have arrived. Like most toads, eggs are laid in long strands and hatch shortly after being laid. This species is known to hybridize with American Toads and hybrids can have characteristics intermediate to both species. Tadpoles will undergo metamorphosis 5–8 weeks after hatching. Juvenile toads will often remain along the margins of wetlands for several weeks after metamorphosing to feed before dispersing.

Habitat: Similar to American Toads, Canadian Toads can be found in most aquatic habitats in their range, but infrequently use ephemeral or temporary wetlands (unlike Great Plains Toads). Semi-permanent or permanent wetlands, lakes, and reservoirs are all common breeding habitat for this species. After breeding, most adults can be found in upland prairie habitats.

Species Range: This distribution of Canadian Toads roughly follows that of the Prairie Pothole Region, extending from northeastern South Dakota and western Minnesota to northern Montana and north into Canadian provinces of Alberta, Saskatchewan, and Manitoba.

South Dakota Range: The Canadian Toad is restricted to the northeast corner of South Dakota.

South Dakota Status: This species is not listed by South Dakota Game, Fish and Parks.

Account written by Drew R. Davis

Distribution Map
Distribution map of Canadian Toad (Anaxyrus hemiophrys)

County level distribution of this species in South Dakota. Map generated from data collected from voucher specimens and photographic records. See About for additional information.

Photographs
Canadian Toad (Anaxyrus hemiophrys)
Canadian Toad (Anaxyrus hemiophrys)
Canadian Toad (Anaxyrus hemiophrys)
Canadian Toad (Anaxyrus hemiophrys)