Habitat Assessment of an Inland Population of the Gulf Coast Kangaroo Rat (Dipodomys compactus)
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I conducted a habitat assessment on an inland population of the Gulf Coast kangaroo rat (Dipodomys compactus) located in Guadalupe County, Texas. Previous research on the Padre Island population of the Gulf Coast kangaroo rat has shown the species to inhabit open areas with deep sand and little vegetation, essentially barren sand dunes. However, this distinct habitat type does not occur inland and yet the species is found in certain areas of inland south Texas. The goal of my study was to determine if the northernmost known population of D. compactus retains the species affinity for deep sparsely-vegetated sand habitat. My study site was the Diamond Half Ranch consisting of approximately 2303.3 ha, located 16 km south of Seguin, x Texas. In order to assess the habitat associations of this inland Gulf Coast kangaroo rat population, 57 points were semi-randomly located across the study site. At each of these points, I used the Daubenmire frame technique to record the percent of ground cover for grass, forbs, small woody plants, litter (dead herbaceous material), and bare substrate (soil, rock) within a 10 m circle centered on the point. I also recorded the average height of the tallest plants, the average tree canopy present at each point using a spherical densiometer, and the number of active (uncluttered opening, feces, tracks, etc) burrow openings. Data were collected in May 2011, August 2011, November 2011, and February 2012. The results indicated a significant difference in microhabitat parameters between points with and points without active burrows present. The differences were due largely to the percent forbs, bare substrate, and tree canopy cover present, as well as the height of the herbaceous vegetation. The percent cover of litter and the percent tree canopy cover were consistently greater at points with active burrows absent while the percent cover of bare substrate was consistently greater at points with burrows present. At the scale of the entire ranch, habitat use (burrow digging) by the Gulf Coast kangaroo rat appears to be correlated with the presence of native plants, disturbed soils, and bare substrate such as grazed and unimproved pastures. The results of my study might aid in searching for additional inland D. compactus populations and development of management practices to sustain current populations.