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Thesis Abstract – Baumler (2010)


Habitat assessment of a newly established breeding pond for the population of Western toads, Anaxyrus boreas, at the Bernard Field Station

Author and college:

Erin A. Baumler, Scripps College


April 26, 2010


Bachelor of Arts in Biology


Marion Preest, Joint Science Department of Claremont McKenna, Pitzer, and Scripps Colleges


This study was the first research endeavor ever conducted concerning the population of Western toads, Anaxyrus boreas, at the Bernard Field Station. Despite the current lack of information regarding this population, they will become a concern in future years because they are threatened by habitat destruction. Preceding this study, a single breeding pond has been available to this population, which has been in use for the past 20 to 30 years. However, it is likely that the current breeding pond will be destroyed and the land will be developed for human use. In order to provide these toads with another breeding site, a new pond was constructed. Its suitability as an aquatic habitat was assessed on the basis of temperature, light intensity, algal growth and sediment levels in comparison to conditions at the old breeding pond. When tadpoles were raised in the laboratory in various water treatments, those reared in water from the new pond showed no decrease in survivorship or growth rate. The only significant difference in growth was between laboratory-raised and field animals. Tadpoles living in the field were both smaller in length during the larval period as well as smaller in mass at metamorphosis. Additionally, 75% of the tadpoles translocated to the new site completed full metamorphosis. Therefore, the new pond is both hospitable and conducive to tadpole development, a positive sign for future conservation efforts.

Thesis availability:

Scholarship@Claremont – http://scholarship.claremont.edu/scripps_theses/136/

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