1. Conservation and Science Department, Lincoln Park Zoo, 2001 N. Clark St, Chicago, IL 60614, USA
2. Committee on Evolutionary Biology, University of Chicago, 1025 E. 57th St, Chicago, IL 60637, USA
3. Center for Species Survival, Smithsonian Conservation Biology Institute, 1500 Remount Rd, Front Royal, VA 22630, USA
4. Prairie Wildlife Research, PO Box 308, Wellington, CO 80549, USA