1. Agriculture and Forestry Experiment Station, School of Agriculture and Land Resources Management, University of Alaska, Fairbanks, Alaska 99775, USA
2. Elk Island National Park, R.R.# 1, Site 4, Fort Saskatchewan, Alberta, Canada T8L 4J6
3. Department of Animal Science, University of Alberta, Edmonton, Alberta, Canada T6G 2P5
4. Department of Biological Sciences, University of Calgary, Calgary, Alberta, Canada T2N 1N4
5. 1952 Glenmore Ave., Sherwood Park, Alberta, Canada T8A 0X5