Humane Wildlife Population Control

Although controversial, contraception and sterilization methods can be used as alternatives to current methods of controlling overpopulation of domestic and wild animals. Immuno-contraception (also known as SpayVac) is a birth control method that uses the body's immune response to prevent pregnancy. It has been used effectively in a number of wildlife species including wild horses in Nevada, white-tailed deer in Ohio, American black bears in South Dakota, Tule elk in California, South African elephants, and llamas and alpacas in Peru. One of the main advantages is that it is non-invasive.

For more information on using contraception to manage wildlife populations, see "Fertility Control of Animals" by Jay F. Kirkpatrick and Allen T. Rutberg.

Dr. Liu and his colleagues, who first reported on the use of PZP in feral and domestic animals in a 1989 article in the Journal of Reproduction and Fertility, are continuing to perform collaborative research with government agencies and non-profit organizations worldwide. The UC Davis researchers are developing PZP and hormone-based agents aimed at effective and humane methods of contraception and sterilization of animals.

While it may not be appropriate to use this method on all reproductive-aged females in a population, it may be advantageous to use birth control on specific females with known conflict histories. In Whistler, the Bear Aversion Research Team discovered that some sows only ended up in conflict when they had cubs; during times when they were solitary, they foraged away from human-use areas on natural foods. Under these circumstances, wildlife officials could prevent the possible destruction of a family by using Immuno-contraception on the sow anytime before she dens. The needle can last one to five years, preventing the fertilized egg from growing just as Mother Nature would if she were not fat enough to sustain the pregnancy.

For more information, please see www.pzinfo.org or contact:

Liu, Irwin K., Professor
Department of Population Health & Reproduction
1114 Tupper Hall, University of California, Davis, CA 95616
Phone: 530-752-1358 Fax: 530-752-4278
E-mail: ikliu@ucdavis.edu