Habitat Preference of Western Diamond-backed Rattlesnakes (Crotalus atrox) at Bosque del Apache National Wildlife Refuge, New Mexico: An Analysis at Multiple Scales

Bosque del Apache National Wildlife Refuge is located in central New Mexico in the Chihuahuan desert. Approximately 25% of the refuge spans the Rio Grande floodplain and consists of managed riparian and agriculture areas. The upland areas are dominated by creosote bush (Larrea tridentata), honey mesquite (Prosopis sp.), and four-wing saltbush (Atriplex canescens). Western diamond-backed rattlesnakes (Crotalus atrox) are habitat generalists of dry lowland areas and commonly use dry washes, Larrea and Prosopis desert, rocky slopes, scrub/grassland, man-made structures, and less commonly hydric habitats. A high diversity of vegetation types span the refuge and hydric and upland habitats are often in close proximity. To determine if C. atrox are found uniformly across the refuge and within their home ranges as well as what habitats are preferred and avoided, we investigate habitat preference at two spatial scales, landscape and home range. We used initial snake captures and search effort data for the landscape and radio-telemetry data for the home range analysis. We found that snakes use habitats non-uniformly at both spatial scales. While snakes at the landscape scale were found more than expected in Riparian habitat, a variety of habitats were preferred and avoided at the home range level. Apparent selection and avoidance was found when grouping telemetered individuals, although, it was not significant. Individual variation within home ranges varied so dramatically that significant average preference or avoidance in certain habitats could not be determined for the telemetered group as a whole. Among individual home ranges, some habitats were preferred by some and avoided by others