Plains Spadefoot Spea bombifrons

Family: Scaphiopodidae

General Adult Description: Adult Plains Spadefoot dorsal coloration ranges from tan to brown to olive gray with a series of irregular dark marks. Often, these dark marks will contain orange to red warts within. Total length of adults is 7–10 cm. The ventral side of adults is white and unmarked. Additionally, this species has a large raised bump (called a boss) between the eyes, large eyes with elliptical (vertical) pupils, and a dark, keratinized spade on the hind legs that are used for digging. Unlike the true toads (Bufonidae), Plains Spadefoots lack a well defined parotoid gland and as smooth to the touch (rather than warty and rough). Adult males have nuptial pads (dark, keratinized pads) on the first and second digits of the forearms that are used to help grasp the female during amplexus (breeding); females lack these pads.

General Larval Description: Tadpoles are usually tan or gray with a faint mottling pattern. Larvae have rapid development (see Reproduction below) and morphological changes are rapid. The vent is medial in these tadpoles (similar to true toads). Overall, the body is large and bulbous with the widest point being just behind the eyes. The tail fin is mostly clear, lacking pigmentation.

Call Description: As explosive breeders, large choruses of these frogs can be heard immediately after heavy rain events. The call is often described as a wail, snore-like bleat, or growl, sounding similar to a “waaah” or “waaac” that is repeated once every one to two seconds.

Behavior: This is a highly fossorial species of frog and that is quite suited for life in arid environments. Like most amphibians, this is a nocturnal species of frog and consumes various invertebrates. When disturbed, Plains Spadefoots can secrete as noxious, distasteful skin secretion than can cause irritation to the eyes and sinuses.

Reproduction: This species is what is considered to be an explosive breeder. During and shortly after heavy rain events adults emerge from burrows and proceed to ephemeral bodies of water to reproduce. Breeding activity is typically intense for one or two days, then adults leave ponds to return to terrestrial habitats. Eggs are typically laid in strands attached to vegetation and hatch in < 2 days. Tadpoles typically undergo metamorphosis within two weeks of hatching.

Habitat: Typically, adult Plains Spadefoots are found after heavy rains when they are out foraging or moving to and from breeding habitats. They can be found in most grassland habitats and are not typically associated with forest or woodlots. Breeding habitats where adults congregate are shallow, often small ephemeral bodies of water that collect in depressions in the landscape or in agricultural fields. Large, permanent ponds are not used by breeding adults.

Species Range: This species can be found across much of the Great Plains from Texas to southern Canada and west into the Rockies.

South Dakota Range: The Plains Spadefoot can be found across a large portion of South Dakota, but appears to be absent from much of northeast quarter of South Dakota.

South Dakota Status: This species is not listed by South Dakota Game, Fish and Parks.

Account written by Drew R. Davis and Jessica L. Speiser

Distribution Map
Distribution map of Plains Spadefoot (Spea bombifrons)

County level distribution of this species in South Dakota. Map generated from data collected from voucher specimens and photographic records. See About for additional information.

Photographs
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)
Plains Spadefoot (Spea bombifrons)