Scaphiopus intermontanus
(Great Basin Spadefoot Toad)

Key Characteristics:

Adult Characteristics

Tadpole Characteristics

Egg Characteristics

Vertical pupils

Dark colored with gold specks

Eggs in small (grape to plum-sized) clusters

"Spade" on
hind feet

Extremely rapid development

Attached to
submerged objects

Smoother skin
than toads

Prominent nostrils

.

Lack parotoid glands

Anteriorly positioned mouth 

.

Slightly upturned nose

Keratinized beak

.

Males call

. .

General Description:
Great Basin Spadefoot Toads are small anurans reaching a size of around 65mm (2.5 in.).  Males are slightly smaller than females. They are variable in color, generally having a ground color of tan, gray or olive. The ground color is usually broken by two lighter colored stripes running down either side of the back, and there may also be spots which are sometimes a reddish-orange color. The ventral color is generally a white or light cream. The black "spade" on each of the hind feet is an easily recognizable characteristic. Other characteristics of the adults include the slightly upturned nose, a bump between the eyes and fairly smooth skin. Great Basin Spadefoot Toads can be differentiated from the other two toad species in Idaho by the absence of parotid glands and the presence of vertical pupils (the other toad species have horizontal pupils). Adults can be found out on moist evenings calling from suitable breeding areas. The males have a call described as a grating "wah" that is given in short repetitive calls.

The egg masses laid by these anurans are small (grape or plum-sized) clumps of pigmented eggs that are generally attached to submerged vegetation or debris. The eggs themselves are around 1mm in diameter and as an adaptation to xeric environments, they develop and hatch very quickly.

The tadpoles of Great Basin Spadefoot Toads are fairly large (up to 70 mm or 2.8 in.) and heavy bodied.  The tadpoles are a pale tan color with golden-metallic specks. The nostrils are dorsally located and prominent. The anteriorly-located mouth has a keratinized beak.

Idaho Distribution:
Great Basin Spadefoot Toads are distributed throughout the deserts, prairies of southern Idaho.

From extreme southern British Columbia, through Great Basin to extreme northwestern Arizona, and from edge of Cascade-Sierra axis east to Rockies.

Habitat:
Great Basin Spadefoot Toads are typically found in arid or semiarid regions. These anurans are usually associated with open habitats such as desert brush and grasslands. Great Basin Spadefoot Toads are adapted to burrowing and may stay buried for many months. The habitats they occupy must have water available at least every few years. The body of water can be in the form of irrigation ponds, rain pools or other shallow lakes and ponds.   Some breeding sites may be in harsh temporal wetlands such as mudflats.

Found from sea level to about 2800 m, on shrub steppe, pinyon/juniper woodlands, and spruce/fir forests, but is restricted to shrub steppe habitats in the Northwest. Uses variety of temporary and permanent waters for breeding.

Diet:
Not well known over entire range. Larvae probably eat algae, organic debris, and plant tissue. Adults are known to eat ants, beetles, grasshoppers, crickets, and flies.

Ecology:
Hibernates/aestivates. Primarily nocturnal, but sometimes forages during day. Digs burrow in loose soil, or uses burrows of small mammals to escape heat and dry periods. Predators include birds and probably fishes. Adult spadefoots have noxious skin secretions known to repel predators and cause sneezing in humans.

Reproduction:
Breeding occurs sporadically from April through July, often after spring or summer rains (in the Northwest, breeding season is irregular in response to local moisture conditions). Female lays eggs in small packets of 20-40; total eggs may equal 300-500. Under optimal conditions, eggs probably hatch in about 2-3 days. Larval period lasts a few to several weeks.

Conservation:

Status:

Unprotected nongame species

Global Rank:

G5

State Rank:

S4


Species description, key characteristics and original work by John Cossel Jr. © 1997
Species ecological information from Groves et al. ©1997.
Original images provided by Charlotte Corkran and Jonathon M. Beck © 1997
Design and Optimization by Ean Harker©1999, 2000.
DAI layout by Stephen Burton, and Mike Legler © 1999.