General accounts of western amphibians list the breeding season of Bufo b. boreas as extending from January through July, the breeding season being later in areas of higher altitudes and latitudes. Factors, other than temperature, which influence the breeding season are seldom (if ever) mentioned. Along the Snake River canyon in eastern Washington and northwestern Idaho, water conditions play such an important role in determining the breeding season of B. b. boreas that temperature appears to have a negative correlation. On the prairies of Whitman and Asotin counties, Washington and Latah County, Idaho, which range from 2000 to 2500 feet elevation, the breeding season of boreas generally varies from the last week of April to the middle [...]