Deer Population ControlDeer Population Control (Non-Lethal):
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Application of PZP to Wildlife

This article is a reprint from the Science and Conservation Center

Wild Horses: The vaccine has been used successfully to manage the wild horse population of Assateague Island Nation al Seashore (ASIS) under the sponsorship of the National Park Service (NPS). This population has been treated for 18 years without any negative side effects and the population has been reduced by 20%, without the removal of animals, since management level application began in 1995. Wild horses are also being managed on Cape Lookout National Seashore, for the NPS, on Carrot Island, NC, for the Rachel Carson National Estuarine Reserve, Little Cumberland Island, GA (private), Pryor Mountain, MT, and Little Bookcliff, CO National Wild Horse Ranges, Return to Freedom Wild Horse Sanctuary, CA, and close to 20 Horse management Areas (HMAs) in the western United States, for the Bureau of Land Management. In addition to controlling the horse population on ASIS, treatment has extended the life span and improved the health of older mares, by removing the stresses of pregnancy and lactation (see Kirkpatrick 1995, 2005a, 2005b; Kirkpatrick and Frank 2005; Kirkpatrick and Turner 2002, 2003; Kirkpatrick et al. 1990c, 1991a,1992a,1995b, 1996a,b, 1997a; Liu et al. 1989; Turner and Kirkpatrick 2002; Turner et al. 1996a, 1997a, 2001, 2002)

Zoo Animals: In order to prevent the production of “surplus” animals, more than 100 species of zoo animals in more than 100 zoos worldwide have been treated with PZP. Thus far PZP has been shown to be effective ein more than 40 species, and the results for the remainder will be clear after larger numbers of animals have been treated. In all probability, PZP will prove to be effective in almost all ungulates (hoofed animals), and some other taxon groups (bears, seals, for example). There are considerable species differences with regard to the timing of booster inoculations. Porcine zona pellucida vaccine is now a standard recommendation for many species by the Contraceptive Advisory Committee of the American Zoo and Aquarium Association (AZA). The obvious advantage of PZP for zoo animals is that it can be administered without the stresses of restraint (see Patton et al. 2005; Frisbie and Kirkpatrick 1998; Kirkpatrick et al. 1995c 1996b; Deigert et al. 2003; Frank 2005, Frank et al. 2005; Liu et al. 1998).

Deer: The PZP vaccine was shown to block pregnancies in captive white-tailed deer as early as 1990. Since that time numerous projects have been mounted with free-roaming deer in seven states. The two largest projects are on Fire Island National Seashore (FINS), NY, where more than 200 deer are treated annually over a 13 year period, and on the campus of the National Institute of Standards and Technology (NIST), MD, where more than 150 deer are treated annually over an 11-year period. On both these programs the deer population has been significantly decreased. The studies thus far have shown that contraception with PZP will extend the breeding season of the female by one to two months, but that the energy cost of getting pregnant and lactating is greater than the extended breeding season. Although young males will follow the treated female deer during the extended breeding season, they do not engage in fights or extend additional energy beyond the normal breeding season (see McShea et al. 1997; Naugle et al. 2002; Turner et al. 1992,1996b, 1997b; Rutberg et al. 2004, 2005).

African elephants: In order to eliminate the need to legally kill elephants in African national parks to prevent rapid population increases, the PZP vaccine has been tested in African elephants in Kruger National Park in South Africa. The vaccine was very successful and the results paralleled those of horse contraception. One of the most important findings was that the vaccine caused no changes in the social behaviors of family groups or harassment of cycling females by bulls. As a result of the Kruger project, small game parks throughout South Africa are now managing more than 400 elephants with PZP, rather than shooting them. Demand for the vaccine by South Africa grew so rapidly, that in 2003, the SCC trained the African team to produce PZP and helped establish a lab in the veterinary school at Onderstepoort (see Fayrer-Hosken 1997, 1999,2000; Delsink et al. 2002, 2004, 2005).

Other Species: The PZP vaccine has also been used successfully in water buffalo inhabiting the U.S. Naval Base in Guam, feral burros in Virgin Islands National Park (see Turner et al. 1996a), and elk on Point Reyes National Seashore, CA (see Shideler eet al. 2002).

Training/Education: The SCC conducts training programs for personnel from NGOs and government agencies, for the proper use of PZP in wildlife. Examples of agencies participating in these training programs include the Bureau of Land Management, Biological Resources Division of USGS, U.S. Fish and Wildlife Service, U.S. Navy, and the National Park Service.

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