Inter- and Intrahabitat Movements of the Rough-Skinned Newt, Taricha torosa granulosa (Skilton)

Abstract

Qualitative data obtained by direct observation is the usual basis for conclusions on various aspects of amphibian life history. The present study involves a technique whereby a temporary pond was fenced and traps were used to study the activities of various species of amphibians. This method enabled maintenance of a record of passage into and out of the pond and correlation of these travels with environmental factors. Some of these quantitative field data plus laboratory and conventional field techniques are here applied to give a more complete picture of certain non-reproductive aspects of the life history of a western North American salamander, Taricha torosa granulosa (Skilton). These observations are related in their reference to movements of these newts. Although this paper is limited to life history considerations, mention of nomenclature used seems appropriate. Recent taxonomic treatments of the genus Taricha (Riemer, 1958; Pimentel, 1958) show differences of opinion regarding the relationship of torosa and granulosa, i.e., are they species, or subspecies of a single species? In addition, Riemer gave good reasons for assigning two previously described subspecies, simulans and twittyi, to the synonomy of granulosa. This seems to be the only possible conclusion from Riemer's work. Elimination of these two races removes the last major problem, distribution pattern, from my interpretation of the relationslhips. I believe two species of Taricha now exist, T. rivularis and T. torosa. T. torosa is represented by two groups of closely related subspecies, the torosa group with torosa and sierrae, and the granulosa group with granulosa and mazamae. The general patterns of the life histories of the two species of western North American Taricha are known (Chandler, 1918; Miller and Robbins, 1954; Riemer, 1958; Ritter, 1897; Smith, 1941; Stebbins, 1951; Storer, 1925; and Twitty, 1942). Taricha behavior does not differ greatly from that of other newts of the family Salamandridae. Part of the year is spent on land and the remainder in water. Land existence is assumed to be a time of subterranean quiescence. Aquatic life is associated with reproductive activity and larval growth. Eggs are laid in water and hatch into aquatic larval stages. The larvae metamorphose and become terrestrial. These immature animals remain on land until they attain sexual maturity. At the next breeding period, the new, as well as old, adults move to water. After adults complete reproduction they again assume an underground life. A