Frog of the Week

Western Toad (Anaxyrus boreas)

Western Toad
photo by Walter Siegmund
least concern


Common Name: Western Toad
Scientific Name: Anaxyrus boreas
Family: Bufonidae – True Toad family
Locations: Canada, Mexico, and the United States
US Locations: Alaska, California, Colorado, Idaho, Montana, New Mexico, Nevada, Oregon, Utah, Washington, and Wyoming
Size: 2.2 – 5 inches (5.6 – 13 cm)

The Western Toad lives in the western North America, from Alaska down to Baja California. There are two subspecies of the toad, the California Toad (A. b. halophilus) and the Boreal Toad (A. b. boreas). The California Toad resides in California (duh), northern Baja California, and western Nevada. The Boreal Toad live in the northern parts of the range.

Once the toad emerges from hibernation, they migrate to temporary ponds filled by the melting snow to breed. Due to the wide range and differences in altitudes, the breeding season is from February to July. Farther north and higher altitude places breed later than more southern and lower altitude places. Once the males arrive at the ponds, they start to sing out for the females. As soon as, the females arrive, the male tries to grab the female from the behind in the amplexus position. If the female accepts, the female lays her eggs. She lays as many as 12,000 eggs in a clutch. Then, the male fertilizes the eggs. Neither parent provides any care for the offspring.

Western Toad
photo from USGS/Chris Brown

Western Toad Conservation

The International Union for the Conservation of Nature (IUCN) Red List categorizes the Western Toad as Least Concern for Extinction. However, some populations of the toad are not doing so hot. Western Toads are listed in Colorado as an endangered species. They are listed as a protected species in Wyoming. Chytrid Fungus, a deadly pathogen, seems to be the main problem for the Western Toads. Additionally, habitat destruction is another problem for the toads.

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