Anaxyrus cognatusGreat Plains Toad

Geographic Range

The range of Great Plains toads stretches from extreme southwest Manitoba, Canada, to southeast Alberta, Canada, and south to Texas; eastern-central Utah to extreme southeast California and far south into Chihuahua, Coahuila, Durango, and San Luis Potosi, Mexico. There is a disjunct colony of Great Plains toads in south-central Colorado.

Habitat

Great Plains toads are common toads of the great open spaces of broad grasslands, and the arid southwest. They are usually found in the lower, damper sections of these areas. These toads frequent irrigation canals, flood plains of rivers, temporary rain pools, and reservoirs.

  • Aquatic Biomes
  • rivers and streams
  • temporary pools

Physical Description

The adult Great Plains toad averages 4.8-9 cm in length. On its back it has large dark blotches. Each blotch is boldly bordered by light pigment and contains many warts. The colors of this toad are generally yellowish, brown, greenish, or gray on top. Below is unspotted, cream to white, with a yellow or orange-yellow seat patch. Some specimens have been found with a narrow, light mid dorsal stripe. The head of the Great Plains toad is relatively small with a well-developed cranial crest. Their snout is blunt and rounded.

Development

Reproduction

The Great Plains toad breeds only after rain storms in spring and summer when the temperature exceeds 12 degrees C. Breeding sites are restricted to relatively clear shallow water, which include buffalo wallows, flooded fields, and the edges of extensive temporary pools. They breed usually in large congresses built up by the reaction of males to one another's call. A calling male clutches any toad that happens to touch him, and once a female is clasped she is retained tenaciously. A single female may lay as many as 20,000 eggs, which are attached to debris near the bottom of temporary pools, permanent springs, and small streams. Roughly two days after laying the eggs hatch. The tadpoles are small when first hatched and grow only to about 25 mm in length. About 1 1/2 months after the eggs are laid, metamorphosis begins and takes less than two weeks to complete. The newly transformed young of the year will not become sexually mature until they are 3-5 years old.

  • Range number of offspring
    20000 (high)
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    1460 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    1460 days
    AnAge

Lifespan/Longevity

  • Average lifespan
    Status: captivity
    10.7 years
    AnAge

Behavior

This species spends a considerable amount of time underground, because the period favorable for activity may last only a few weeks in the spring or summer. The toads burrow by backing into the ground with a shuffling movement of the hind feet. The Great Plains toad is nocturnal but sometimes diurnal, especially during the breeding period. Usually, however, they come out of their burrows about an hour before dusk. When annoyed this toad may assume a defensive attitude common to many anurans. The lungs are inflated, thereby increasing the size of the body; the head is lowered and the eyes are often depressed into their sockets.

Food Habits

The Great Plains toad is an insectivore with a diet that includes, moths, flies, cutworms and beetles. Of its prey, cutworms pose the biggest problem to humans. This toad is known to be important to agriculture because they eat cutworms and many other noxious insects that feed on and damage crops. The Great Plains toad is nocturnal, thus feeds at night, which makes it hard to observe their food habits.

Economic Importance for Humans: Positive

The Great Plains toad is an effective enemy of over-wintering cutworms in Oklahoma. Their value to agriculture on a yearly basis in Oklahoma has been estimated at $25 per individual toad.

Conservation Status

In order to protect this species its natural habitat must be protected. In many states in the Great Plains region there are laws in place that protect the plains. To ensure the continued survival of this species this protection of habitat must continue.

Contributors

Elizabeth J. Axley (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

agricultural

living in landscapes dominated by human agriculture.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry. This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots.

ectothermic

animals which must use heat acquired from the environment and behavioral adaptations to regulate body temperature

external fertilization

fertilization takes place outside the female's body

fertilization

union of egg and spermatozoan

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

metamorphosis

A large change in the shape or structure of an animal that happens as the animal grows. In insects, "incomplete metamorphosis" is when young animals are similar to adults and change gradually into the adult form, and "complete metamorphosis" is when there is a profound change between larval and adult forms. Butterflies have complete metamorphosis, grasshoppers have incomplete metamorphosis.

motile

having the capacity to move from one place to another.

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Conant, Roger and Joseph T. Collins. 1991. A Field Guide to Reptiles and Amphibians: Eastern and Central North America. Houghton Mifflin Company, Boston, MA.

Krupa, James J. 1990. Advertisement call variation in the Great Plains toad. Copeia 3: 884-886.

Krupa, James J. 1989. Alternative mating techniques in the Great Plains toad. Animal Behavior 37: 1035-1043.

Stebbins, Robert C. 1951. Amphibians of Western North America. University of California Press, Berkeley, CA.