Great Plains Toad (Anaxyrus cognatus)

Great Plains Toad
Anaxyrus cognatus

by Jeff LeClere

An adult Great Plains toad, Anaxyrus cognatus, from Fremont County, Iowa.

An adult Great Plains toad, Anaxyrus cognatus, from Fremont County, Iowa.

Status

No status assigned in Iowa.The scientific name was formerly Bufo cognatus.

Description

This is a large toad species reaching 3 1/2 inches in body length. Adults are white, gray, or yellowish with several large oblong spots on the back. These spots, often paired, are gray, brownish, or greenish in color and contain many small warts. Some specimens have a white mid dorsal stripe down the back. The underside is plain white or light colored with no markings. The cranial crests are far apart and touch the roundish parotoid glands at the back of the head. In the front, they converge to form a boss, or a ‘bump’ on the snout.

Subspecies

There are no subspecies of Anaxyrus cognatus recognized.

Range

The Great Plains toad is found only in western Iowa. Records are documented from every county on the western border, and quite a few on the second counties to the east.


Habitat

Great Plains toads are found in open grasslands, prairies, and cultivated fields. They need water in which to breed in the form of temporary or permanent water. Large wetlands to irrigation ditches to even puddles are used. I have commonly heard males calling and have seen breeding activity in flooded plowed farm fields.

Habits

These toads are mostly active at night, especially in hot, humid weather. They spend most of their time underground in burrows they dig themselves with a tough spade-like projection on their hind feet. Spring rains induce the toads to breed. They migrate to the breeding sites in May and the males begin to call. The call is like an American toads’, but it is more mechanical and riveting sounding. The inflated vocal sack is sausage shaped and extends upward past the snout. Males call and breeding activity may occur sporadically from May into July, especially during and after rains. Breeding may not occur during dry years. Females lay strings of thousands of eggs which the male fertilizes externally. Tadpoles transform in 1 1/2 to 2 months. They may emerge from their burrows at other times of the year such as at night during periods of high humidity or during heavy thunderstorms, again mostly after sunset.

Food

They eat any small insects or earthworms and even feed on harmful invertebrates in agricultural areas. This may also harm them as they inadvertently ingest pesticides and absorb other chemicals living in and near farm fields.

An adult Great Plains toad, Anaxyrus cognatus, from Fremont County, Iowa.

An adult Great Plains toad, Anaxyrus cognatus, from Fremont County, Iowa.