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Canadian Amphibian and Reptile Conservation Network - Réseau Canadien de 
Conservation des Amphibiens et des Reptiles

Spea intermontana

formerly Scaphiopus intermontanus

Great Basin Spadefoot / Crapaud du Grand Bassin


Great Basin Spadefoot

Description
Spadefoots differ from other frogs and toads by their vertical pupil, relatively smooth skin, teeth in their upper jaw and absence of parotoid glands. They also have a horny, sharp, dark edged knob or tubercle (the "spade") on the inner surface of the hind foot. The Great Basin Spadefoot is a stout bodied animal with a glandular hump between the eyes. The spade is wedge shaped. The skin is fairly smooth gray-green to olive with numerous small scattered bumps which may be orange. There may be light stripes on the flank. The belly is white. Adults can grow to 5 cm.

Call
The call is a series of short harsh nasal sounding snores. The time between each snore is approximately the same as the length of the snore.

Confusing Species
The Tailed Frog also has vertical pupils but does not have a tympanum and lives in very different habitat. The Plains Spadefoot looks very similar, however, the hump between the eyes is bony rather than glandular and the spade may be round or wedge-shaped. Fortunately their ranges do not overlap -- the Plains Spadefoot is not found in British Columbia.

Distribution
The Great Basin Spadefoot is restricted to the Okanagan and Thompson/Nicola valleys of southern British Columbia. It is more widely distributed through the Great Basin of the western United States, as far south as Arizona.

Habitat
The Great Basin Spadefoot is found in arid areas with loose soil near its breeding sites. In British Columbia it breeds in vernal ponds and semi-permanent alkali lakes.

Reproduction
Breeding is triggered by substantial rain which fills breeding sites. Eggs hatch in less than a week and the tadpole stage is relatively brief.

Natural History
Great Basin Spadefoots are nocturnal. They avoid the heat and dryness of the day by burrowing underground with their spades. They emerge on mild, damp evenings to forage and breed.Sometimes they are brought to the surface by driving over or stamping near their burrowing site. It is believed that they mistake the vibrations for the sound of heavy rain falling. Spadefoots also spend the winter burrowed underground.

Conservation Concerns
The Great Basin Spadefoot appears to have declined throughout its range in British Columbia. It is vulnerable to habitat destruction by cattle and recreational vehicles. The Great BasinSpadefoot is designated Threatened by COSEWIC