Abstract

Understanding the spatial ecology of an animal is crucial for making positive efforts to provide for its recovery. As a part of this understanding, home range estimates are used to answer a variety of questions in ecological studies. However, home range estimates based on a collection of radio-telemetry locations are sensitive to methodological variables, such as sample size, sampling frequency, and the choice of estimator. Further confounding these estimates are a number of physical, social, and ecological factors. Identifying the main determinants of space use patterns by a species may aid conservation efforts.

The Desert Tortoise (Gopherus agassizii)of the Mojave Desert inhabits an extreme environment where a number of factors likely influence its land use patterns. Prior home range estimates of the Desert Tortoise are wide ranging from different portions of the desert, due in part to the use of a variety of sampling methodologies. My goal was to determine how different facets of sampling methodology affect home range estimates of the Desert Tortoise using two widely-used home range estimators, the minimum convex polygon and the fixed kernel density estimator. In addition, investigated physical, social, and ecological variables to examine the dominant factor(s) influencing the spatial ecology of the Desert Tortoise.

Results suggested that previous home range estimates were highly influenced by the sampling regime utilized. Home range estimates in this study were much greater than those in the literature, possibly due to an intensive sampling regime. This suggests that tortoises may require more land than previously thought. Males and females demonstrated very different patterns of space and burrow use, suggesting these variables affect estimates for each sex differently. I conclude that a combination of these variables determines space use in tortoises. By adopting a uniform sampling methodology, researchers can better provide comparable data across studies in a holistic effort to understand the spatial ecology of a species.

LLU Discipline

Biology

Department

Biology

School

School of Science and Technology

First Advisor

William K. Hayes

Second Advisor

Stephen G. Dunbar

Third Advisor

Andrew D. Walde

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2007

Date (Title Page)

12-2007

Language

English

Library of Congress/MESH Subject Headings

Tortoise -- Ecology; Home range (Animal geography) -- Mathematical models; Zoogeography -- Mathematical models; Animal ecology.

Type

Thesis

Page Count

xii; 97

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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