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Plains Spadefoot

(Spea bombifrons)

Identification: Pupil vertically elongate (like a cat’s) in bright light; a single hard, wedge-shaped spade on each hind foot; hard lump between eyes, slightly forward of an imaginary line crossing the middle of both eyes; upper side often with a roughly hourglass-shaped marking (four light lines; often absent in smaller individuals); adult head and body length up to about 6 cm (2.4 inches).   Mature male: Dark patches on inner 2–3 toes of front feet during the breeding season; expanded vocal sac slightly two-lobed.

Breeding call :  A brief snore, much faster than the long, stuttering snore of the New Mexico spadefoot.  

Larvae: Upper side brown or green to whitish, or mottled gray and dull olive yellow, usually of pale appearance, sometimes with bluish iridescence; upper tail fin clear or with sparse yellowish and gray mottling/flecks; lower fin clear or mainly clear with sparse yellow flecks; body globular; eyes close together on top of head; belly iridescent golden, gut coil not visible (large larvae); jaws frequently cusped, lower jaw not striated; jaw muscles sometimes greatly enlarged and may bulge from the sides of the face in front of the eyes; usually 3-4 rows of tiny teeth on upper lip and 4 rows on lower lip; usually up to 7 cm (2.8 inches) total length, sometimes up to 9.5 cm (3.7 inches).

Eggs: Deposited in elliptical masses of about 10–250, attached to submerged plants or other objects.    

Colorado Distribution: Plains of eastern Colorado and the San Luis Valley. Probably occurs in the valley lowlands of western Montezuma County. Common.    

Habitat: Breeds in pools and stock ponds filled by heavy rains, in plains grassland, sandhills, or semidesert shrubland.    

Life History: Spends most of its life buried in the soil. Emerges to breed after heavy rains in spring or summer. Larvae develop quickly and metamorphose into small toads usually within 3-10 weeks.