1. Department of Biological Sciences, California State University, Chico, Chico, CA 95929
2. Department of Mathematics and Statistics, California State University, Chico, Chico, CA 95929
3. United States Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, CA 95620
4. United States Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, Vallejo, CA 94592