1. Department of Biology, Regis University, Denver, CO 80221, USA
2. Department of Animal Welfare and Research, Denver Zoo, Denver, CO 80205, USA
3. Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH 03824, USA
4. Department of Animal Care, Denver Zoo, Denver, CO 80205, USA
5. Birmingham Zoo, Birmingham, AL 35223, USA
6. Reproductive Health Surveillance Program, Morrison, CO 80465, USA