Evaluation of Population Density and Characterization of Suitable Habitat for the Gulf-Coast Kangaroo Rat (Dipodomys Compactus)
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The Gulf-coast kangaroo rat (Dipodomys compactus) is characteristic of the arid ecosystems of South Texas and the barrier islands. It is listed by Texas Parks and Wildlife Department as a species of concern and is the only member of the family Heteromyidae found on Mustang Island, North and South Padre islands, Texas, and the barrier islands of Tamaulipas, Mexico. I conducted my study at Padre Island National Seashore, to investigate this poorly understood species. I estimated population density and distribution, characterized burrow microhabitat, and used Geographic Information Systems (GIS) to compare transects with different kangaroo rat densities. Live-trapping using mark-recapture methodology was conducted for two periods between April 2010 and October 2010 along 12 transects. A variety of microhabitat characteristics of burrows were measured on active burrows. Trap success for the entire sampling period was 5%, but more individuals were caught during the spring sampling period than the fall sampling period. Using the Lincoln-Peterson index, I estimated a population density of 3.6 individuals per hectare. Active burrows differed significantly in slope, type of vegetative cover, and percent vegetative cover compared to paired random locations. Burrows were found in areas with a higher slope and less vegetative cover. Low trap success and coarse scale ecogeographical layers made development of a habitat suitability model difficult. A more intensive study over a longer time frame will be essential to effectively delineate habitat and predict population sizes.