Adult Description: Overall, Canadian Toads are similar in appearance to American Toads. Canadian Toads are a medium-sized toad with adults being approximately 3 inches (7.5 cm) in length and 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 reddish orange or brown 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 behind the eye and are fused together between the eyes to form a raised, bony structure called a boss. Parotoid glands are often kidney-shaped but can be 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 when they are breeding and have a dark throat; females lack these pads and have a pale throat. This species can be easily identified from other South Dakota toads by having a mottled underside (Woodhouse’s Toads and (Great Plains Toads have white undersides) and the presence of a boss between the eyes (American Toads lack a boss and have cranial crests extending behind the eye).
Larval Description: Larval Canadian Toads can be difficult to distinguish from tadpoles of other species of toads. 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, that is often described as less musical and harsher that the call of American Toads.
Call Example: Canadian Toad calls (Day County)
Habitat: 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.
Natural History: The Canadian 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 below the frost line (30–71 inches deep) to avoid freezing temperatures. To defend themselves, Canadian Toads can inflate their bodies to make themselves appear larger, present the parotoid glands that discharge a milky toxic secretion, or urinate on a predator. This species breeds from late May to June and typically arrives at wetlands after Boreal Chorus Frogs have arrived. As females lay eggs, males release sperm to externally fertilize up to 20,000 eggs that females can produce. Like most toads, eggs are laid in long strands and hatch shortly (1 week) after being laid. 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.
Species Distribution: 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 the Canadian provinces of Alberta, Saskatchewan, and Manitoba.
South Dakota Distribution: The Canadian Toad is restricted to the northeast corner of South Dakota.
South Dakota Status: This species is not monitored by South Dakota Game, Fish and Parks.
Remarks: This species is known to hybridize with American Toads and hybrids can have characteristics intermediate to both species. Contrary to popular belief, toads cannot transmit warts to humans by touching them.