Assessment of Sterilization as a Non-lethal Deer Management Option in Urban/Suburban Landscapes

Project Background

Dense populations of white-tailed deer coupled with urban/suburban expansion has led to increased human-deer conflicts.  These conflicts result in significant economic losses associated with deer-vehicle collisions, tick-borne pathogens, and landscape damage.  The most effective and efficient solution is to lower deer densities through removal of individuals from the population.  Historically lethal removal (i.e., sharpshooting, hunting, or live-capture and euthanasia) has been the accepted management action for population reduction.  However, when suburban communities are faced with the need to lower deer densities, non-lethal control options are often preferred because of legality, safety concerns, and social attitudes related to lethal management.

In theory, immunocontraceptive vaccines provide a non-lethal method for reducing deer numbers by lowering female fertility.  However, single-shot forms of these vaccines have not been shown to effectively reduce deer populations and follow up booster shots are required to extend the period of effectiveness.  Surgical sterilization is currently the only reliable means to permanently sterilize females and may be a viable option for reducing deer populations where lethal removal is impractical.  Moreover, while the initial cost for sterilization is substantial, it has been suggested that sterilization programs precluding the need for recapture will provide long-term cost savings.  The purpose of this research is to provide an evaluation of the cost and effort required for an urban deer sterilization program and to assess the subsequent deer population-level effects.  In addition, we will compare cost and effort of surgical sterilization with that of administering an immunocontraceptive vaccine.

Project Overview

The sterilization study sites are located in Virginia, New York, and California, whereas the immunocontraceptive vaccine site is in North Carolina.  Deer have been and will continue to be captured at each site over the next two years.  At the surgical sites ovariectomies will be performed by a licensed veterinarian and the vaccine used at the other site will be GonaConTM.  Populations will be monitored and population-level impacts will be recorded.

Effort will be recorded for each site as the total time spent by the capture team each night.  These times will be separated into subcategories of pursuit, search, and transport, with transport only being relevant to the surgical sterilization projects.  These data will allow us to determine what percentage of total capture time is spent searching or transporting deer after they have been darted with an immobilizing drug.   It has been hypothesized that if vaccines could be administered remotely it would make them significantly more cost-effective.  Although GonaConTM is currently registered for hand injection only, the USDA-National Wildlife Research Center is considering labeling it for dart delivery.  If the label change were allowed, this would reduce costs associated with capture and hand injection of the vaccine, but there currently is no permanent marking mechanism that would provide subsequent identification of treated females.  Multiple injections of immunocontraceptive vaccine to the same female would result in unnecessary costs and likely would make any saved handling costs negligible.

Project Objectives

1)      Provide a case study of a deer sterilization program in Fairfax City, Virginia.

2)      Assess population-level effects of deer sterilization programs on three different sites in the USA, each at a different stage since implementation (i.e., 1, 2, or 3 years since implementation).

3)      Evaluate the cost and effort of sterilization programs as compared to vaccines (both hand-injected and remotely injected).

Project Funding

The proposed research will be conducted in conjunction with and funded solely by Dr. Anthony J. DeNicola of White Buffalo, Inc.  White Buffalo, Inc. is the leading expert in population control of deer in highly sensitive areas such as suburban communities and city parks.  It is a nonprofit wildlife management and research organization.  They sponsor, support, and conduct scientific research and educational efforts to improve the understanding of natural resource management for the purpose of conservation.

Principle Investigator: Charles S. Evans

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Temporary surgical site located at the Fairfax City Police Department

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Two females a few days after surgical sterilization in Fairfax City, VA