Description: It has a white or cream dorsal stripe, and is dusky gray or greenish dorsally with skin glands concentrated within the dark blotches. Its parotoid glands are oval, widely separated, and larger than the upper eyelids. It has a mottled venter and horizontal pupils but lacks cranial crests. Compared to females, males have smoother skin, reduced dorsal blotching, and nuptial pads (thickened skin) on their forefeet during breeding season. In juveniles of this species, the dorsal stripe is weak or absent. Large young have prominent dorsal and ventral spotting and yellow feet.
Habitat: The boreal toad is found in the Rocky Mountains in aspen (Populus spp.) groves and riparian forests. In Colorado, the largest populations are typically found in areas characterized by willows (Salix spp.), bog birch (Betula glandulosa), and shrubby cinquefoil (Potentilla fruticosa). In the Pacific Northwest, the western toad occurs in mountain meadows and less commonly in Douglas-fir forests (Pseudotsuga menziesii).
In California, optimum habitat for the western toad includes wet or dry mountain meadows or riparian deciduous forest with available open water for breeding. Suitable habitat includes blue oak (Quercus douglasii) savanna, gray pine-oak forest (Pinus sabiniana-Quercus spp.), mixed conifer forest, and alpine meadows. Marginal habitats include annual grasslands, chaparral, ponderosa pine forests, California black oak woodlands, Jeffrey pine forests, and red fir forests.
In the Sierra Nevada, the western toad occurs in mid-elevation pine forests (including Jeffrey pine (Pinus jeffreyi) at higher elevations and ponderosa pine (Pinus ponderosa) at lower elevations), California black oak woodlands (Quercus kelloggii), giant sequoia groves (Sequoiadendron giganteum), montane fir forest (which includes white fir (Abies concolor), red fir (Abies magnificaPinus monticola)), and redwood forest (Sequoia sempervirens). It is also found in riparian areas within sagebrush-pinyon communities (Artemisia spp.-Pinus spp.), oak-pine woodland and savanna (including coast live oak (Quercus agrifolia), interior live oak (Quercus wislizenii), and canyon live oak (Quercus chrysolepis)), and California coastal forest and scrub.
Western toads have been collected from sedge meadows near a pond occurring in a creosotebush (Larrea tridentata) community, and from aspen (Populus spp.)-willow groves within big sagebrush (Artemisia tridentatav)-grassland.
Range: The range of the western toad extends from western British Columbia and southern Alaska south through Washington, Oregon, and Idaho to northern Baja California, Mexico; east to Montana, western and central Wyoming, Nevada, the mountains and higher plateaus of Utah, and western Colorado. Occurrences of the boreal toad from Yukon Territory, the Northwest Territories, and northwestern and north-central British Columbia have been reported. Southern records of boreal toads in New Mexico have been published.
Diet: Western toads wait for their prey on the surface of the ground or in shallow burrows dug by other animals. Their diet consists largely of bees, beetles, ants, and arachnids. Other foods include crayfish, sow bugs, grasshoppers, trichopterans, lepidopterans, and dipterans.
Reproduction: In central Oregon, the minimum breeding age for male western toads is three years, and probably four or five years for females. California toads are reported as sexually mature at 2 years of age. Male western toads breed every year; females breed at less regular intervals, depending on individual condition and previous years' breeding effort. Sex ratios differ according to habitat type; males are more numerous in wet areas and females are more numerous in dry habitats.
Eggs are laid in open water from February to July, with peak activity occurring in April. Timing of egg-laying activity varies with elevation and weather conditions. In Colorado, initiation of breeding was correlated with the onset of warming weather and initiation of snowpack melting. Eggs are usually laid in late May or early June. In western Montana, a few males were present on the shores and were spaced at least 1 foot apart, all facing the shore. Eggs are laid in gelatinous strings of 13 to 52 eggs per inch, in masses of up to 16,500 per clutch. Egg development rate is partially dependent on temperature; hatching times vary.
Metamorphosis is usually completed within three months of egg laying. The time required for metamorphosis is given as 30 to 45 days for the boreal toad and 28 to 45 days for the California toad.
Female western toads at least 10 to 11 years of age have been reported. In Colorado, boreal toads probably attain a maximum age of at least 9 years.
Status: The western toad occupies a variety of habitats and is presently listed as a species of least concern. Nonetheless, concerns remain about the impact of disease and chemical contamination of the environment, especially chytridiomycosis. One of the chief chemical threats is the overuse of urea as fertilizer, which is often applied in high dosage to forest environments to increase biomass productivity and economic return. A. boreas is harmed by the dermal absorption of this chemical, which can lead to increased mortality.
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Disclaimer: ITIS taxonomy is based on the latest scientific consensus available, and is provided as a general reference source for interested parties. However, it is not a legal authority for statutory or regulatory purposes. While every effort has been made to provide the most reliable and up-to-date information available, ultimate legal requirements with respect to species are contained in provisions of treaties to which the United States is a party, wildlife statutes, regulations, and any applicable notices that have been published in the Federal Register. For further information on U.S. legal requirements with respect to protected taxa, please contact the U.S. Fish and Wildlife Service.
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