1. U.S. Fish and Wildlife Service, Division of Migratory Birds, 500 Gold Avenue SW, Albuquerque, NM 87103, U.S.A.
2. U.S. Fish and Wildlife Service, Science Applications, 500 Gold Avenue SW, Albuquerque, NM 87103, U.S.A.
3. Department of Natural Resources Management, Texas Tech University, 15th and Detroit, Mail Stop 42125, Lubbock, TX 79409, U.S.A.
4. U.S. Fish and Wildlife Service - Intermountain West Joint Venture, University of Montana, 32 Campus, FOR302, Missoula, MT 59812, U.S.A.