1. Caesar Kleberg Wildlife Research Institute, Texas A&M University-Kingsville, 700 University Boulevard, MSC 218, Kingsville, TX 78363, USA
2. Natural Science Division, Pepperdine University, 24255 Pacific Coast Highway, Malibu, CA 90263, USA
3. Arizona Game and Fish Department, 555 N. Greasewood Road, Tucson, AZ 85745, USA
4. Borderlands Research Institute, Sul Ross University, P. O. Box C–16, TX 79832, USA