SMALL MAMMAL AND BIODIVERSITY RESEARCH
Translocation of the Black-tailed Prairie Dog in West Texas
The black-tailed prairie dog was once widespread and abundant in far west Texas, but populations have declined since the early 1900s and they have been largely extirpated from Brewster County, Texas. The decline of prairie dog populations from poisoning, plague, and habitat conversion and fragmentation coincided with an increase in woody species, such as honey mesquite. Research suggests that this is due, at least in part, to these aggressive woody shrubs being able to colonize new, available habitat after the grazing pressure of prairie dogs has been eliminated.
An excavator and manual clearing was used to remove mesquite from the release site. This would allow the trans-located prairie dogs the line-of-sight that they rely on to avoid predators while also removing potential cover or perches that predators may use.
Despite their potentially significant role in maintaining healthy grasslands, there has been very little research done on black-tailed prairie dogs in Trans-Pecos Texas. Because of this, we started a project on a private ranch in Brewster County, Texas, where prairie dogs had occurred historically, but there were currently no existing colonies on the ranch at the time of the study. Our research objectives included 1) restoring habitat in a desert grassland, 2) translocating a small population of prairie dogs, 3) conducting a vegetation inventory, and 4) monitoring of prairie dogs post-translocation.
We chose a translocation site which would meet the habitat requirements of prairie dogs, and restored the area by clearing over 200 acres of mesquite. We also mowed the area directly surrounding the release site to allow the newly released prairie dogs to detect predators.
We released 200 individual prairie dogs over the course of three translocation events. The survival rate of the translocated animals was less than 10 percent. This was less than we expected, and we believe it was due to a number of factors including stress, unexpected precipitation, potential territorial behavior, and the lack of a pre-existing colony.
The vegetation inventory included measuring woody species occurrence, estimating mean canopy cover, and surveying mesquite plants to document potential herbivory. Sampling was conducted before and after mechanical brush removal and before and after translocation. We found that woody species decreased overall in dominance and frequency after brush removal, and we observed one instance of broken branches on a monitored mesquite plant.
We also conducted visual surveys and burrow surveys to monitor the prairie dogs post-translocation. We used the results of this study to develop a habitat model for the prairie dog in Trans-Pecos, Texas, and a total of 385,324 acres of ‘Best Habitat’ were determined available for colonization. Restoring habitat for translocation of a native population of prairie dogs within their historic range can potentially aid in the restoration of an ecosystem, and future research on an established black-tailed prairie dog population would enable researchers to assess and evaluate the impacts of this keystone species in a desert grassland ecosystem.