| Great Basin Spadefoot | |
|---|---|
| Conservation status | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Amphibia |
| Order: | Anura |
| Family: | Scaphiopodidae |
| Genus: | Spea |
| Species: | S. intermontana |
| Binomial name | |
| Spea intermontana (Cope, 1883) |
|
The Great Basin Spadefoot (Spea intermontana) is a species of toad in the Scaphiopodidae family.
Contents |
The Great Basin Spadefoot ranges from 3.8 to 6.3 cm long. It is usually gray, olive, or brown colored. Gray streaks outline an hourglass shaped marking on the back. The skin is smooth compared with the bumpy skin of the true toads in the genus Bufo. There is a spade present on the inside of each hind foot; it has sharp edges and is wedge-shaped. A glandular boss is present between the eyes. Eyes are catlike; pupils are vertical in bright light and round at night. Dark brown spots are present on each upper eyelid.
The natural habitats of the Great Basin Spadefoot include pinyon-juniper, ponderosa pine, and high elevation spruce-fir forests, semidesert shrubland, sagebrush flats, temperate grasslands, and deserts. They are present in agricultural areas as well. The Great Basin Spadefoot can be found from southern British Columbia through the eastern portions of Washington and Oregon and in southern Idaho. Their range extends throughout all of Nevada and into most of Utah; they are also present in small areas in California, Arizona, Colorado, and Wyoming.
Breeding is explosive, meaning that large congregations of individuals assemble and mate with each other. Adults are terrestrial and must migrate to breeding sites. Breeding may take place in permanent or temporary water sources such as springs, sluggish streams, and manmade reservoirs during the months of April through July. Males call and attract females to breeding sites. Once females arrive, there is a race to mate with as many others as possible, and physical contests between males are common. Females usually lay 300-500 eggs, but have been reported lay as many as 1000 eggs in captivity. Eggs are attached to vegetation present in the water or placed at the bottom of the pool. Eggs hatch in 2 to 4 days, and the larval period lasts an average of 36 days. Tadpoles may be carnivorous or herbivorous, depending on environmental conditions. Different larval diets are associated with different morphological characteristics.
Adults have been shown to eat arthropods from the taxa Coleoptera, Diptera, Hemiptera, Hymenoptera, Lepidoptera, Neuroptera, Orthoptera, Trichoptera, Collembola, and Araneae. Ants and beetles are their most common prey. Feeding seems to be generalized and opportunistic; the toads will eat anything they can subdue.
Reported predators of adult Great Basin Spadefoot toads include rattlesnakes, coyotes, and owls. Predators of larva include crows, trout, and garter snakes. Adults are able to produce skin secretions that cause allergic reactions in some humans, including a burning sensation if the secretion gets in the eyes or nose. Some researchers believe the skin secretions deter predators.
Great Basin Spadefoot toads have adapted to life in dry habitats. Desiccation is avoided by this terrestrial amphibian through burrowing into the ground. The Great Basin Spadefoot uses the hard, keratinized spade on each foot to dig a burrow, where it spends long periods during cold and dry weather. The toad is able to absorb water from the surrounding soil; even as the soil becomes increasingly dry in spring and early summer months, increased concentrations of urea in the toad's body allow it to continue to suck water out of the soil through osmosis. When the summer rains arrive the Great Basin Spadefoot is able to emerge from its burrow.