1. Department of Range and Wildlife Management, Texas Tech University, Lubbock, Texas 79409, USA
2. Current address: The Nature Conservancy of Texas, P.O. Box 315, College Port, Texas 77428, USA
3. Current address: Caesar Kleberg Wildlife Research Institute, Texas A&M University–Kingsville, Kingsville, Texas 78363, USA
4. Department of Pathology, Texas Tech University Health Sciences Center, Lubbock, Texas 79430, USA
5. Current address: Savannah River Ecology Laboratory, The University of Georgia, Drawer E, Aiken, South Carolina 29802, USA