Alberta SRD - Fish and Wildlife - Wildlife in Alberta - Amphibians of Alberta

Great Plains Toad

Last Review/Updated: May 30, 2002

Bufo cognatus

Description

The great plains toad is slightly smaller than the western toad, ranging in length from 45-110 mm. The toad is covered in dark blotches, each of which contain small warts, on a background of pale browny-grey or olive. The belly of the toad is whitish and without spots. The great plains toad can be identified by its cranial crests. The crests are quite obvious starting at the snout and diverging behind the eyes. The Canadian toad also has prominent cranial crests but they tend to be parallel or joined at the back.

Natural History

The great plains toad is active from April to September in Alberta. Although primarily nocturnal, it sometimes forages on cloudy, rainy days. It prefers habitats with loose soil to allow burrowing, which it does to avoid high temperatures. Like the western toad, it will inflate itself if threatened and raise itself on its legs. It also tends to lower its head when threatened. Prey items include moths, flies, beetles and cutworms. The great plains toad is currently on the Red List in the Status of Alberta Wildlife because it is considered to be in serious trouble. Populations are nonviable or are at serious risk of declining to nonviable levels. Recent research indicates that there may be fewer than 2000 adults in the province.

Breeding

After spring or summer rains, breeding occurs in temporary ponds, ditches, or almost any flooded area. Males congregate in breeding ponds and begin calling. The sound is quite loud and can carry up to 2 km on the prairies. The great plains toad prefers clear shallow water and it will not breed in muddy water. Up to 20 000 eggs may be laid by a single female in long strings, which are generally attached to debris on the bottom of the pool of water. The eggs hatch roughly two days later.

Larvae

The tadpoles are small when first hatched and grow only to about 25 mm in length before transforming in about six weeks time. Although the back may be a mottled brown and grey or black, the tadpoles have a light green underside. The newly transformed young of the year will not become sexually mature until they are 3-5 years old.

Distribution

The great plains toad is quite rare in Alberta, where it exists at the northernmost part of its range. It is restricted to short-grass prairie environments and most sightings are from the South Saskatchewan River and its tributaries. It is also found in the extreme southwest corner of Saskatchewan.

Monitoring

Great plains toads are primarily nocturnal, making them difficult to locate outside of the breeding season. In the spring, adults will congregate at breeding ponds and begin calling.