Effects of SpayVac® on Urban Female White-Tailed Deer Movements

Abstract

High white-tailed deer (Odocoileus virginianus) densities in urban areas typically result in human-wildlife conflicts (e.g., deer—vehicle collisions, transmission of disease to humans, and vegetation damage). Controlling deer densities via fertility control generally is more acceptable than lethal removal in many urban areas and can reduce conflicts by stabilizing deer numbers. Contraceptive vaccines that use PZP (porcine zona pellucida) proteins as antigens have been used for many years and generally are regarded as safe and effective. Side effects of immunocontraception may be repeated estruses, an extension of the breeding season, and increased movements and ranges of immunized deer. We evaluated the effects of SpayVacTM, a long-lasting, singledose PZP vaccine on ranges and movements of female white-tailed deer at the Lyndon B. Johnson Space Center near Houston, Texas, USA. We captured, treated, and radiomarked 38 female deer with SpayVac (treatment) and injected 11 deer with a placebo (control). Fawning rates for treated and control deer were 0% and 78%, respectively. We observed no difference in the movements and ranges of SpayVac- versus placebo-treated deer: annual ranges (95% probability area) between treated (x̄x = 82 ± 7 ha) and control (x̄x = 77 ± 14 ha) deer, core areas (50% probability area) between treated (x̄x = 11 ± 1 ha) and control (x̄x = 11 ± 3 ha) deer, and daily movements treated (x̄x = 430 ± 1.5 m) and control (x̄x = 403 ± 3.6 m) deer. However, we did not evaluate the potential effect of immunized females on ranges and movements of male white-tailed deer. Increased ranges and movements may be more pronounced for males than for females.