1. New Mexico Cooperative Fish and Wildlife Research Unit, Department of Fish, Wildlife and Conservation Ecology New Mexico State University Las Cruces NM 88003 USA
2. Department of Fish, Wildlife and Conservation Ecology New Mexico State University Las Cruces NM 88003 USA
3. U.S. Army Construction Engineering Research Laboratory Champaign IL 61826 USA
4. U.S. Geological Survey, New Mexico Cooperative Fish and Wildlife Research Unit, Department of Fish, Wildlife and Conservation Ecology New Mexico State University Las Cruces NM 88003 USA