An Investigation into the Life History and Habits of Ensatina eschscholtzii eschscholtzii
author: Helen Leslie McKay
advisor: Charles A. Reed
ABSTRACT: The object of this thesis was an investigation of the life history and habits of Ensatina eschscholtzii eschscholtzii, by studying, collecting, and experimenting upon members of this subspecies found in the "canyon" on the Reed College campus, Portland, Multnomah County, Oregon.
Results of the attempts to determine growth rate and age groups were largely negative; however, a young age group was established and its growth followed for a period of some six months. A new minimum size of 24.5 mm. was found for the young and a new record for their collection, on November 1, 1945, was made. Population density, particularly in correlation with habitat, was investigated and a new type of covering, moss, under which the salamanders may often be found, was added to the list of likely locations for the collection of specimens. The type of food eaten was determined by analysis of the contents of the digestive tracts, swimming behavior was determined by experimentation, and the first observation of production of sound by this species was made. An attempt was made to study movement in the natural environment, but the results were not sufficiently extensive to draw many conclusions. Some information in the form of quantitative data was added to the existing knowledge on autotomization and regeneration of the tail, and some data as to size of eggs, size of female, number of eggs, and time of year were collected.
Many questions about the life history and habits of this species remain unsettled and some new ones have been raised. It is hoped that the new information that has been added will prove useful to future investigators and to the general observer of Urodeles, but more particularly it is hoped that this thesis will act as a guide for future investigations by pointing out the existing problems.