1. H. T. Harvey and Associates Ecological Consultants Los Gatos California 95032 U.S.A
2. Department of Earth Sciences University of Minnesota Minneapolis Minnesota 55455 U.S.A
3. Department of Biological Science University of Alberta Edmonton Alberta TG6 2E9 Canada
4. Wildlife Research Division, Science and Technology Branch Environment Canada 5320 122 Street Edmonton Alberta T6H 3S5 Canada
5. Institute of Arctic and Alpine Studies University of Colorado at Boulder Boulder Colorado 80309 U.S.A
6. Department of Ecology, Evolution, and Behavior University of Minnesota St. Paul Minnesota 55108 U.S.A