1. US Geological Survey, New Mexico Cooperative Fish and Wildlife Research Unit, New Mexico State Univ.; Las Cruces NM USA
2. Dept of Fish; Wildlife and Conservation Ecology, New Mexico State Univ.; Las Cruces NM USA
3. Centre for African Ecology, School of Animal, Plant and Environmental Sciences, Univ. of the Witwatersrand; Wits South Africa
4. School of Natural Resources and the Environment, Univ. of Arizona; Tucson AZ USA
5. Dept of Animal Sciences; Univ. of Arizona; Tucson AZ USA
6. School of Agricultural Sciences, Northwest Missouri State Univ.; Maryville MO USA
7. Dept of Animal and Range Sciences; New Mexico State Univ.; Las Cruces NM USA
8. Arizona Game and Fish Dept; Yuma AZ USA
9. US Fish and Wildlife Service, Cabeza Prieta National Wildlife Refuge; Ajo AZ USA