Ovariectomy As a Management Technique for Suburban Deer Populations

Abstract

ABSTRACTOverabundant suburban deer (Odocoileus spp.) are a source of human‐wildlife conflict in many communities throughout the United States. Deer‐vehicle collisions, impacts to local vegetation, tick‐borne pathogens, and other negative interactions are typical reasons cited for initiating deer management programs. Social attitudes, legal constraints, and perceived safety concerns lead many communities to examine nonlethal management options. Surgical sterilization is currently the only nonlethal method available to permanently sterilize females with a single treatment. However, there are limited data demonstrating methods and outcomes in management programs that sterilize a high percentage (>90%) of local populations of females, particularly regarding the impact of immigration on non‐isolated populations. We present data from 6 surgical sterilization sites with geographically open populations in California, Maryland, Michigan, New York, Ohio, and Virginia, USA. From 2012 to 2020 we sterilized 493 deer, primarily via ovariectomy, and conducted annual or periodic population estimates using camera surveys, road‐based distance sampling, and intensive field observations to assess population trends. Study sites ranged from 1.2 km2 to 16.5 km2 with ~47–169 individuals, resulting in approximate densities of 6–63 deer/km2. For all sites we noted an average reduction of ~26% (17%–36%) from Year 1 to Year 2. Four years after initial treatment, we documented an average population reduction of ~45% (29%–56%). During the first year, the average cost per deer sterilized at locations where bait was used was US$1,185 ($927–$1,572). Surgical sterilization projects demonstrate that significant reductions in local deer densities using high‐percentage, surgical sterilization programs can be achieved in non‐insular locations, where baited deer are approachable by vehicle for darting. Sustained sterilization efforts may be necessary, as is the case with all deer management programs, in areas where immigration is possible, and all the animals are not sterilized. © 2021 The Wildlife Society.