Comprehensive DescriptionRead full entry
The European, American, or Plains Spadefoot Toad is a small but rotund toad-like frog, generally resembling true toads (Bufonidae) in body form. Spea bombifrons can grow up to 2¼" in snout-vent length (Colorado Herpetological Society 2002). Its skin, which is relatively smooth, can range from gray to brown, sometimes with a greenish hue, and is scattered with darker spots or blotches. The skin is also smoother and thinner than that of Bufonidae. Along the dorsal and lateral surfaces run four vague light stripes, the middle two of which occasionally resemble an hourglass. There are many small tubercles on the otherwise smooth skin. The ventral surface is white and has no markings, although the throat of the male is bluish or grayish on the sides (USGS 2002). There is a raised, bony lump (boss) between the large eyes. The eye has an elliptical, vertical, cat-like pupil, and thus differs from the true toads, whose pupils are round. S. bombifrons also differs from Bufo in that it has no parotid glands (or, when present, they are indistinct) (USGS 2002). Like the other members of the family Pelobatidae, or the spadefoots, S. bombifrons is named for its large, well-developed, wedge-shaped, sharp-edged, black tubercle or metatarsal "spade" on the bottom of each hind foot. This bony element, which is capped with a keratinous cover, is used to burrow rear-first (USGS 2002).
Substantial population declines observed during extended droughts are more likely a result of non-breeding during suboptimal environmental conditions than true population declines (Cottonwood 1986).