Incorporating Desert Tortoise Line Distance Sampling Data from Mojave Desert Biologic Surveys into a Geographic Information System

Publication Date


Committee Chair

Karen K. Kemp, Ph.D.

Committee Members

Jill S. Heaton, Ph.D.
Glenn G. Hyman, Ph.D.


The desert tortoise is designated as a ‘threatened’ species by the United States Forest Service. The designation of ‘threatened’ has prompted numerous studies of the tortoise’s habitat, factors that may pose threats to the tortoise, and tortoise population densities. Biological surveys of where and how many desert tortoises exist provide critical information for managers who must make decisions on a daily basis that effect planning the continued viability of the desert tortoise.

Line distance sampling was selected by the Desert Tortoise Management Oversight Group as the method of choice for part of a multi-year project to determine desert tortoise population densities range wide for the desert tortoise. This research demonstrates that incorporating data from those biologic surveys in a geographic database will extend data accessibility and analysis capabilities for research of desert tortoise habitat. Spatial analysis will support researchers by providing science-based estimates of the desert tortoise habitat preferences. Inclusion in the dataset of geomorphologic, land cover, and elevation data for estimating desert tortoise habitat preferences will extend the research value of the line-distance sampling database. The database will aid in the understanding, access, and communication of desert tortoise habitat information that can be used to support conservation activities, and associated decision-making processes. By establishing a consistent methodology and automating many of the processing steps, future iterations of the project will produce a consistent, cost-effective database.

Full text is available at the University of Redlands


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