Notes on the Western Spotted Frog, Rana pretiosa pretiosa

Abstract

T HE western spotted frog is perhaps one of the most common and widely distributed frogs in Washington, yet little seems to be known concerning its life history. It is found throughout the state according to Slevin (1928) and occurs on both sides of the Cascade Range. Storer (1925) referred specimens from Walla Walla and the Blue Mountains, Washington, to the subspecies luteiventris rather than pretiosa. Slevin did not recognize luteiventris as a separate subspecies but placed it in synonymy with pretiosa. This conclusion was evidently based on the work of Van Denburgh and Slevin (1915), who were unable to find sufficient differentiation between the adults of R. pretiosa pretiosa from Mount Rainier, Washington, and R. p. lutezventris from Utah for separation. Further work on the interrelations and distribution of these subspecies is obviously needed. Personally, I am not familiar with luteiventris, but I have found a distinct difference in the mouth parts of pretiosa tadpoles and those pictured for luteiventris tadpoles. Since the eggs of luteiventris have not yet been described there may be still further differences between the two. In Washington the spotted frog seems to be more abundant west of the Cascades than on the eastern side. This is due no doubt to the greater humidity and number of permanent streams on the west side, for this frog is rarely found far from water. As Dickerson (1906) and Blanchard (1921) have both noted, it is a pond dwelling form and very aquatic in habits. In eastern Washington, particularly in the vicinity of Pullman, the spotted frog is found along the Palouse River and in such roadside pools as are formed during the construction of the highways. These roadside pools are well filled with water in the spring, and here the spotted frogs congregate for the breeding season. Even at this time of the year they are not abundant and are never found in such large numbers as the tree frog Hyla regilla. This corroborates Blanchard's observations on the spotted frog in Stevens County, Washington. In the vicinity of Pullman the first amphibian to appear in the spring is the long-toed salamander, Ambystoma macrodactylum, which may be found, according to the season, late in January or early in February. The spotted frog emerges a few weeks later, usually late February or early March. By the middle of March and early April the breeding season is in full swing, and mating pairs as well as eggs in all stages of development can be found. The breeding season extends into the middle of April. After this time it is usually impossible to find eggs or even adult frogs. Soon after the spotted frog makes its appearance in the spring, mating commences, and the ponds are resonant with their deep bass calls. Their short bass notes are easily distinguishable from the almost constant high