Efficacy of surgical sterilization for managing overabundant suburban white‐tailed deer

Abstract

Based on decades of increasing deer effects on local biodiversity, agricultural damage, and deer-vehicle collisions, we implemented a suburban white-tailed deer (Odocoileus virginianus) research and management program in 2007 on Cornell University lands in Tompkins County, New York, USA. We attempted to reduce deer numbers by surgically sterilizing female deer in the 445-ha suburban core campus via tubal ligation and ovariectomy. From 2007 to 2013, we sterilized 93 deer and radiocollared 67 adult females to monitor fawning. Tubal ligation and ovariectomy surgeries appeared to prevent birth in 96% and 100% of treated female deer, respectively. We implemented a camera survey, used a mark-resight model in Program NOREMARK to estimate annual deer abundance, and observed no reduction in female abundance by winter 2013. Conversely, we noted a 38% and 79% decrease of total adult females and fawns visible in sampled photographs, respectively, and an 873% increase in adult male visitation to camera traps on core campus. Surgical sterilization appeared to be ineffective for reducing the abundance of a geographically open population of white-tailed deer in the absence of lethal management. We do not recommend surgical sterilization as a stand-alone method for communities wishing to pursue mitigation of deer impacts with nonlethal approaches. Ó 2016 The Wildlife Society.

Red oak seedlings as indicators of deer browse pressure: Gauging the outcome of different white‐tailed deer management approaches

“…Despite hundreds of deer taken by hunters on Cornell lands and doe sterilization rates of >90%, our camera surveys indicated that by 2012, five years into the program, we had not achieved any reduction in the core deer population (Boulanger & Curtis, ). In response to our failure to reduce the deer population, we eliminated sterilization efforts and established a larger core management area (CMA, approx.…”

“…Animal rights and animal welfare organizations have long claimed that deer are not responsible for lack of forest regeneration and that there are more humane methods for managing populations (HSUS, , ; PETA, ). However, there is no evidence to date that can support claims that fertility control alone can sufficiently reduce deer abundance in free‐ranging populations (Hobbs & Hinds, ; Raiho, Hooten, Bates, & Hobbs, ; Ransom, Powers, Hobbs, & Baker, ), including our own (Boulanger & Curtis, ). Examples cited as success stories show reduced fertility on islands or in fenced populations (Naugle, Rutberg, Underwood, Turner, & Liu, ; Rutberg, Naugle, Thiele, & Liu, ).…”

“…Despite hundreds of deer taken by hunters on Cornell lands and doe sterilization rates of >90%, our camera surveys indicated that by 2012, five years into the program, we had not achieved any reduction in the core deer population (Boulanger & Curtis, 2016).…”

“…We saw no evidence that fertility control is a viable tool for reducing herbivore populations or browse rates on Q. rubra seedlings in a fragmented suburban landscape. Despite a >90% doe sterilization rate and near elimination of deer fawns in our sterilization zone, the deer population remained stable due to immigration, particularly of bucks (Boulanger & Curtis, ). There was no reduction in the browse intensity on oak seedlings (Figures and ).…”

Ethical management of wildlife. Lethal versus nonlethal control of white‐tailed deer

“…Surgical sterilization is an irreversible way of controlling fertility, requiring veterinary involvement. Evidence of efficacy of this method in population reduction is not conclusive; other deer may move in from outside, and sterilization is expensive and difficult to use on a larger scale (Boulanger & Curtis, ). While acknowledging that research on effectiveness of surgical sterilization is ongoing, we will not consider this option further.…”