Distribution Of The Texas Kangaroo Rat (Dipodomys Elator) In Texas; With Comments On Microhabitat, Habitat, And Habitat Modeling
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The Texas Kangaroo Rat (TKR, Dipodomys elator) is a species of concern in Texas with sightings in only seven counties in the past 30 years. The decline of TKR has been attributed to habitat loss, although its exact habitat requirements have not been determined. Habitat studies have focused on microhabitat and burrow associations but have failed to create an accurate landscape level habitat model. Multiple species within the genus Dipodomys have demonstrated strong associations with certain soil and land- cover classes. My goal was to determine which soil and land-cover classes are associated with TKR and then use these associations to model potential TKR habitat across their historic 11-county range. During the summers of 2016 and 2017, I surveyed with spotlights at night for TKR on public roads throughout its historic range. I found TKR at 75 and 63 locations in 2016 and 2017, respectively, among five counties. For analysis, random points were generated along the roads surveyed in 2016 to create a dataset of points representing TKR absence. A two-group randomization test was used to determine if percent composition of soil and land-cover classes (within 150 m buffers surrounding the points) were significantly different between 2016 presence and absence points. Presence points had a greater proportion of mixed grass/shortgrass prairie land-cover class (P < 0.1), cropland land-cover class (P < 0.05), clay loam and loam as the topmost soil layer (P < 0.05), and friable clay as the underlying soil (P < 0.05) than did absence points. A potential habitat model based on where selected land-cover and soil classes overlapped was created using GIS software and the USDA-NRCS Soil and TPWD TEMS databases. This model portrays a more confined range than that shown by previous modeling efforts.