Thesis

Some Aspects of the Life History of the California Newt, Taricha torosa

The purpose of this study was to document the reproductive phase of the life history of Taricha torosa, particularly the migration to and from the breeding pond. Twitty (1966) conducted a similar study with Taricha rivularis. He removed individual newts from portions of their breeding creek and released them at points of varying distances from site of capture. He found they could return from as far away as 12.8 kilometers. In this study a more natural approach was taken. No previous studies have attempted to show the distance a newt travels in the course of its normal migration. Migration of salamanders both toward and away from the breeding pond was documented by various marking techniques . After marking, all animals were immediately returned to their exact point of capture. In this way a more realistic picture of the migratory pattern was obtained. In an effort to discover the stimulus for migration, various physical and biological factors were studied to determine if there were any correlations between these factors and the number of salamanders found abroad. The physical factors included rainfall, day-length, and ambient temperature. The biological factors included body temperature, thyroid activity, feeding habits and gonad weight.

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