Toad is a common name for certain members of the amphibian order Anura, the frogs. The distinction is not firm, but the word toad is generally applied to frogs with relatively short legs and thick bodies, dry, often "warty" skin and reduced webbing between the toes. Toads live in drier habitats than most other frogs. Most toads belong to the family Bufonidae, which occurs naturally on all continents except Antarctica, Greenland and Australia (but one species has been introduced and has spread widely since the mid-1930s in Australia, the West Indies and some Pacific Islands).
In Canada 4 or 5 species of genus Anaxyrus (formerly included in Bufo) are known: western toad (A. boreas), Great Plains toad (A. cognatus), Fowler's toad (A. fowleri), American toad (A. americanus) and Canadian toad (B. hemiophrys), regarded as a subspecies of A. americanus by some authorities.
Two so-called "spadefoot toads," belonging to the more primitive family Pelobatidae, are known in Canada. These are the Plains spadefoot (Spea bombifrons) occurring in Alberta and Saskatchewan and the Great Basin spadefoot (S. intermontanus) in British Columbia and in prairies habitats. Both Anaxyrus and Spea have "spades" on each hind foot, which allow them to burrow backwards rapidly in soft soils.