Sul Ross State University

Evaluating Landscape-Level Changes
of Mule Deer Habitats in Trans-Pecos, Texas

by Ryan Walser, Clay Brewer (Texas Parks and Wildlife Department) and Louis A. Harveson

Desert mule deer (Odocoileus hemionus crooki) were once abundant in the Trans-Pecos Region of Texas.  However, over the past 20 years desert mule deer populations have been declining.

The objectives of this study are to:

1. evaluate habitat changes (e.g., brush encroachment, habitat fragmentation, and changes in land-use patterns) relative to trends of desert mule deer populations;
2. explore relationships between precipitation indices and trends of desert mule deer populations; and
3. assess trends of harvest characteristics in desert mule deer (e.g., quantity and quality).

Data has been collected across the Trans-Pecos ecoregion which is approximately 7.3 million ha and is bordered to the east by the Pecos River, to the west and south by the Rio Grande, and to the north by New Mexico.

Over 25 years of spotlight surveys (1978-2003) for desert mule deer has been collected from nine counties (El Paso, Hudspeth, Culberson, Reeves, Pecos, Terrell, Brewster, Presidio, and Jeff Davis) in the Trans-Pecos region by Texas Parks and Wildlife Department. Five to 10 32-km spotlight surveys have been established in each of the counties.

A landscape-level analysis of changes in habitat composition, habitat fragmentation and land-use patterns will be conducted. Remotely-sensed imagery will be acquired from three periods that correspond to changes in mule deer abundance.

Analysis of precipitation and concurrent drought conditions will be conducted with the help from the National Climatic Data Center (NOAA) and Palmer indices

 Data collected from NOAA will be converted to a series of Palmer indices to evaluate their usefulness to predict population changes. Analysis of the number of mule deer being harvested over time, and the quality of bucks harvested will be evaluated using trends analysis at a county and regional scale.

Cooperative funding provided by Texas Parks and Wildlife Department, Boone and Crockett Club and Sul Ross State University.