Anaxyrus cognatus

The upper surface has a somewhat symmetrical pattern of large, light-edged dark spots. The skin has numerous small warts. Cranial crests (hard ridges) are prominent between eyes and diverge posteriorly from a hard lump on top of the snout. The parotoid glands (glandular swellings behind the eyes) are much longer than wide. The underside of each hind foot often has a sharp-edged tubercle and a smaller dark-tipped tubercle. Females grow up to 4.5 inches (11.4 cm) snout-vent length, while males usually are less than 3.7 inches ( 9.5 cm). During the breeding season, breeding males have dark, loose throat skin and a dark patch on the inner surface of the thumb. The male's expanded vocal sac is large, elongated, and may extend upward in front of the face. The breeding call is a long, continuous trill or pulsating ringing sound lasting at least several seconds; at close range it is similar to the ear-splitting sound of a jack-hammer. The sound varies somewhat with temperature and size of male; loud nasal quacks sometimes precede the trill. Juveniles have reddish warts, and recently metamorphosed toadlets may be as small as 1 cm. Larvae are initially blackish, then become more pale and mottled brown and gray dorsally; under magnification, the dark skin may have an overlying golden suffusion. The pattern of large paired blotches on the back appears before metamorphosis is complete. The eyes of larvae are high on the head, and the dorsal fin is highly arched. The fins are clear with some black branching lines, mainly in the upper fin. Sometimes there is extensive mottling in the upper and lower fins. The tail musculature lacks an unpigmented band along the lower margin. Larvae may grow up to at least 1.4 inches (3.5 cm) in total length. Eggs are black above, whitish below, about 1.1-1.2 mm in diameter. Usually eggs are in a single row in long strings of two-layered jelly that is constricted between the eggs; partitions separate the eggs from each other. Source: Hammerson (1999).

Great Plains toads inhabit deserts, grasslands, semidesert shrublands, open floodplains, and agricultural areas, typically in stream valleys. When not active on the surface they usually occupy underground burrows. Breeding sites include rain pools, flooded areas, and ponds and reservoirs that fluctuate in size. Eggs and larvae develop in shallow water (usually clear). Calling males sit along the shoreline or brace themselves on submerged plants.

Postmetamorphic young may form aggregations (J. Herpetol. 27:315-319).

Breeding occurs after warm rains in spring or summer. Male breeding choruses in a particular site usually last at least a few days but are of variable duration (up to two weeks or more) (Krupa 1994). Females toads are more likely to mate with males that call frequently. However, some males may sit quietly near calling males and sometimes intercept and successfully mate with females approaching the calling male. Individual females deposit clutches of several thousand eggs in shallow water. Larvae hatch in a few days and metamorphose in 2.5-7 weeks. Breeding pools do not hold water long enough for larvae to reach metamorphosis (Krupa 1994). Individuals become sexually mature in 2-5 years. In Oklahoma, this toad commonly exhibited communal egg deposition (Krupa 1994).