1. Department of Animal Science, University of California, Davis, California 95616
2. Division of Biological Sciences, University of Montana, Missoula, Montana 59812
3. Department of Natural Resources, Cornell University, Ithaca, New York 14850
4. Flathead Lake Biological Station, University of Montana, Polson, Montana 59860
5. Center for Watershed Science, University of California, Davis, California 95616