Sul Ross receives $113,000 grant for wildlife habitat study

ALPINE Sul Ross State University's Borderlands Research Institute was recently awarded a four-year, $113,000 grant to study the effects of herbicide on habitat use and movement of mule deer and other wildlife.

The grant, awarded by the Buena Vista Foundation, Austin, provides funding to the BRI to study the effects of the herbicide Spike 20P on mule deer, scaled quail and other wildlife populations in the Trans-Pecos region.

Research will be conducted on Boracho Peak Ranch, located east of Van Horn in Culberson and Jeff Davis counties.

"Since mule deer and scaled quail populations have declined at the landscape level in recent years, it is reasonable to conclude that broad-scale habitat change, especially brush encroachment, is a likely candidate for the changes," said Louis Harveson BRI director and professor of Natural Resource Management.

To combat brush encroachment on natural habitat, the herbicide Spike 20P (tebuthiron) has been commonly used. Harveson, who is the principal investigator for the project, said the research will seek to determine the effects of grassland restoration on wildlife populations.

Boracho Peak Ranch encompasses nearly 100,000 acres, is located in the center of the Trans-Pecos and contains a variety of vegetation types.

Research will determine how wildlife adapt to habitat restored through the use of herbicides, specifically Spike 20P (tebuthiron). The study will also determine movement between areas of land treated with Spike 20P and untreated areas.

"Resource specialists with the Natural Resource Conservation Service commonly prescribe Spike as an option for controlling invasive brush species," Harveson said. "Despite the increased interest and use of Spike, few data are available regarding its' effectiveness to reclaim desert grasslands and more importantly what affect Spike has on wildlife populations."

"Because of the widespread use of Spike, the economical importance of wildlife in the region, and the lack of technical information, our goal is to evaluate the effects of Spike 20P applications on populations of mule deer, scaled quail, and other wildlife," Harveson said.

Research will compare mule deer density and use of habitats between Spike treated plots; assess scaled quail and other wildlife use of habitats relative to treatments; and evaluate the effects of Spike 20P on key forage species for wildlife.

Mule deer will be captured using net-gunning from a helicopter. Upon capture, mule deer will be physically restrained, blind-folded and processed. Mortality sensitive radio-transmitters will be affixed to each captured mule deer and a series of measurements will be taken. Aging will be based on tooth eruption and wear. Twenty mule deer will be captured in February-March 2009 and another 20 in 2010 for this study.

Helicopter surveys will be conducted annually to determine mule deer density within each treatment area (Richardson 2002). Helicopters will fly in a north-south orientation during the first three to four hours of morning and the last two hours of the evening. Two observers will accompany the pilot during surveys.  Observers will count all deer in the survey zone and input geographic data into a handheld iQue (a personal data device) presently used by Texas Parks and Wildlife Department. Locations, age, gender, fawn productivity and geographic locations of all sighting will be imported into the GIS for comparison purposes.

Coveys of scaled quail will also be recorded during the fall helicopter survey. Additionally, scaled quail abundance will be estimated using distance sampling by walking perpendicular lines within the treatment plots. Number of birds/covey and the distance from the line will be recorded to estimate density. All incidental observations of scaled quail will be recorded to support density estimates derived from helicopter counts and line transects. Density estimates, encounter rates (number of coveys/hour) will be compared between treatment plots.

"The Boracho Peak Ranch offers a unique opportunity to conduct this study," Harveson said. "The owners have been aggressive in restoring grasslands to the ranch using Spike 20P. The scale of the application lends itself to study."

"Many times wildlife studies are restricted by the size of their treated areas which may limit their ability to monitor large mammals or birds because of their mobility," he said. "Since Spike has been applied over the last three to four years, it has resulted in four to five blocks with different amounts of time following treatment."