Deer: Sterilization

STERILIZATION
(The IDNR does not support this method in free-ranging contexts.)

Sterilization involves the permanent loss of fertility to a deer. There are two primary forms of sterilization: surgical sterilization and ligation. Surgical sterilization involves the removal of a doe's ovaries. Removal of a doe's ovaries re-shapes doe behavior: there is some indication that sterilized deer move more than fertile deer. Ligation of the oviduct does not alter female behavior but does increase the amount of time she cycles per season.

EFFICACY: Effective in small pockets (less than 2 square miles) and isolated areas with limited immigration opportunity. Some studies suggest that sterilization is more effective than culling because the sterilized deer are able to contribute to resource limitation and density-dependence in reproduction (Boone and Wiegert 1994). Other studies suggest the sterilization is an effective way to maintain a desired population level after culling has been implemented (Nielsen 1997). This method does not eliminate current damage, as population remains; however, it does stem population growth. Higher mortality rates have been observed in sterilized deer; home range size and movement tend to be similar between sterilized and non-sterilized animals (Skinner 2007).

Cornell is currently engaging in research to determine if surgical sterilization in combination with hunting can mitigate deer-related impacts on university lands and surrounding neighborhoods (Curtis 2011). For its study, Cornell divided their management areas into three zones: 1) suburban campus core; 2) adjacent outlying areas that contain agriculture fields and natural areas where deer hunting is permitted and 3) an adjacent control zone. Each zone uses a different technique. In the suburban zone, biologists are using sterilization as the primary management tool. In the agricultural/rural zone, hunting is allowed and the increased harvest of female deer is encouraged through an "Earn-a-Buck" program. The results of the on-going research could determine if fertility control combined with hunting is a viable, long-term approach to managing deer or other wildlife populations.

COST: $800-$1,000/doe plus ongoing maintenance.

SAFETY: No real threat to human safety.

MAINTENANCE: Requires annual maintenance.

HUMANENESS: Because this method works by decreasing fertility rather than increasing mortality rates, this method is generally considered humane.

IDNR: Does not support this method in free-ranging environments.

TASK FORCE POSITION: Because this technique is not approved by the IDNR in free-ranging environments and is costly, this is not a viable option.