The Problem

Since the early 1900s, wildlife conservation efforts

in the United States have focused on restoring,

protecting, and managing many wildlife populations.

In some cases, such as with white-tailed deer and

Canada geese, these efforts have been so successful

that species have become locally overabundant.

Overabundant species cause various conflicts with

people, ranging from minor nuisance issues to serious

habitat and crop destruction, disease spread, and

collisions with vehicles and aircraft.

Traditionally, State fish and wildlife agencies have used

hunting and trapping to manage wildlife populations.

However, in urban and suburban areas where most

human-wildlife conflicts occur, these management

practices are often legally restricted, impractical, or

socially undesirable. Wildlife fertility-control methods,

including contraceptives such as chemosterilants,

devices, and immunocontraceptives, can help

manage conflicts from locally overabundant wildlife

populations when used as part of an integrated

management approach.

Science-Based Solutions

Wildlife contraceptives and other fertility control

methods are promising new tools for managing wildlife

populations and diseases. Scientists at the National

Wildlife Research Center (NWRC)—the research arm

of the Wildlife Services program in the U.S. Department

of Agriculture’s (USDA) Animal and Plant Health

Inspection Service (APHIS)—work with State fish

and wildlife agencies, universities, zoos, international

organizations, and private partners to develop, test, and

register fertility-control methods.

Such tools alone, however, cannot quickly reduce

overabundant wildlife populations to healthy levels.

Instead, they are most effective when used together

with other wildlife management methods, such as

trapping, relocation, population management, or

hunting. Immediate population goals can only be

met by removing problem animals. Fertility-control

methods can then be used in some situations to slow

the rate of population recovery or maintain populations

at desired levels.

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disease management. For instance, brucellosis is

a bacterial disease that causes abortions, infertility,

and lower milk production in bison, elk, and cattle.

Brucellosis is transmitted during the birthing process.

The injectable GonaCon Immunocontraceptive Vaccine

may reduce the spread of brucellosis by preventing

reproduction in infected bison. Similarly, scientists are

investigating an approach that combines rabies and

contraceptive vaccines to reduce stray dog populations

and rabies in developing countries.

NWRC scientists strive to develop wildlife

contraceptives and other fertility-control

methods that are:

▘ Safe for the target species, nontarget

species, and the environment

▘ Free of undesirable side effects

▘ Safe for human consumption if ingested

while eating animal products

GonaCon Immunocontraceptive Vaccine

Target Species:

White-tailed deer (Odocoileus virginianus) and

wild or feral horses (Equus caballus) and burros

(Equus asinus)

GonaCon has also been tested successfully in elk,

bison, feral swine, prairie dogs, ground squirrels,

cats, and marsupials (kangaroos, brushtail possums,

and wallabies).

Application Method:

Injection by hand or remote dart

How It Works:

GonaCon stimulates the production of antibodies

against gonadotropin-releasing hormone (GnRH)—

a key reproductive hormone needed to produce

estrogen and progesterone and to trigger ovulation.

By binding to GnRH, the antibodies reduce GnRH’s

ability to stimulate the release of these sex hormones.

As long as a sufficient level of antibody activity is in

the bloodstream, sexual activity is decreased, and

vaccinated animals remain infertile.

Effectiveness:

During field studies in New Jersey and Maryland with

free-ranging deer in semi-enclosed urban settings, a

single, hand-injected dose of GonaCon was 67 to 88

percent effective at preventing pregnancy the first year

and 47 to 48 percent effective the second year. Some

female deer have remained infertile for up to 5 years

in pen studies. A second dose of the vaccine can be

given to extend contraceptive effectiveness. Additional

research is needed to determine how often deer will

need to be re-vaccinated to remain infertile for their

reproductive lifetime.

In horses, a single, hand-injected dose of GonaCon

has been shown to significantly reduce mare fertility,

resulting in 25 to 45 percent fewer foals being born

over 2 to 3 years. Current research is determining

the best time for re-vaccination to maintain

infertility and whether injection by dart impacts

the vaccine’s effectiveness.

Registration Status:

USDA holds two product registrations for GonaCon

(GonaCon Immunocontraceptive Vaccine and

GonaCon-Equine) through the U.S. Environmental

Protection Agency (EPA). These registrations allow

vaccine use in adult female white-tailed deer and wild

or feral horses and burros. For GonaCon to be used

in a specific State, it must be registered with the State

and approved for use by the State’s fish and game or

natural resource agency. In 2015, GonaCon-Equine

was licensed to SpayFIRST! to produce and distribute

the vaccine.

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vaccine for use with

mammals, such as whitetailed deer and wild or

feral horses.

EPA regulates GonaCon, which is a restricted-use

pesticide. Only USDA Wildlife Services or State wildlife

management agency personnel or individuals working

under their direct supervision can use it. They must

strictly follow all requirements on the product label.

OvoControl P—Oral Bait

Target Species:

Feral pigeons (Columba livia)

Application Method:

Oral, bread-like bait pellet often distributed with a

broadcast feeder

How It Works:

OvoControl P contains 0.5 percent nicarbazin.

Nicarbazin affects egg hatchability by weakening the

yolk membrane, which allows the albumin and yolk to

mix. When OvoControl P is fed to pigeons during their

breeding season, it reduces the number of offspring

produced. The effects are fully reversible, and when

OvoControl P is withdrawn, egg production and

hatchability return to normal within a few days.

Effectiveness:

Under ideal conditions, with all target birds eating

the proper dose of OvoControl P, no new chicks are

hatched. However, during actual field use, not all

targeted birds may consume the bait. So, some chicks

may still be observed, but the numbers would be

greatly reduced. Field observations of treated pigeon

populations have shown up to a 50-percent reduction

in flock population within 1 year.

Registration Status:

OvoControl P is registered by the EPA and is

produced and distributed by Innolytics, LLC.

Who Can Use It:

OvoControl P is classified as an unrestricted or

general use pesticide. Users must strictly follow all

requirements on the product label.

Contraceptive Safety

NWRC adheres to all Federal, State, and tribal human

health and environmental standards when registering

pesticides, drugs, and vaccines. NWRC extensively

tests its fertility control methods, which meet or excee

the EPA’s rigorous safety standards. There are no

known dangers associated with humans or wildlife co

suming animals treated with GonaCon or OvoControl P

Future Research

Future NWRC research will focus on products that

cause permanent sterility with one application. For

instance, scientists are investigating compounds to

reduce the number of ovarian eggs in mammals, such

as free-roaming dogs and feral swine. Other efforts wi

help expand existing product registrations, develop

improved contraceptives and oral delivery systems, an

determine how fertlity control can be used to prevent

wildlife disease spread.

Overabundant feral

pigeons and other

wildlife can cause

serious damage to

natural habitats,

agricultural crops,

and urban landscapes.

The active ingredient in OvoControl P (nicarbazin) weakens the

yolk membrane, causing the yolk and albumin to mix.
USDA is an equal opportunity provider, employer, and lender.

Mention of companies or commercial products does not imply

recommendation or endorsement by USDA over others not

mentioned. USDA neither guarantees nor warrants the standard

of any product mentioned. Product names are mentioned solely to

report factually on available data and to provide specific information.

Photo credits: The images in this brochure were taken by USDA

employees.

This publication supercedes Miscellaneous Publication No. 2035,

“Solutions Through Science: Wildlife Contraceptives,” which was

issued in January 2010.

Program Aid No. 2208

Issued November 2016

www.aphis.usda.gov/wildlifedamage/nwrc

About the National Wildlife

Research Center

NWRC is the only Federal research facility in the

United States devoted entirely to developing effective

wildlife damage management methods. The Center

applies scientific expertise to address human-wildlife

conflicts involving a range of issues: agriculture, human

health and safety, property damage, invasive species,

and threatened and endangered species. NWRC

scientists strive to find solutions that are biologically

sound, environmentally safe, and socially responsible

for use in resolving wildlife damage management

problems. Often, the Wildlife Services’ operational

personnel help NWRC scientists develop and evaluate

new management tools and methods.

NWRC employs more than 160 scientists and support

staff at its headquarters in Fort Collins, CO, and at

field stations throughout the United States. NWRC’s

scientists have expertise in animal behavior, chemistry,

economics, epidemiology, genetics, immunology,

population modeling, reproductive physiology,

statistics, toxicology, wildlife biology, wildlife sensory

biology, and veterinary medicine.

NWRC researchers are investigating compounds that cause

permanent sterility in mammals, such as free-roaming dogs and

feral swine.

More Information

For more information on the development of wildlife

contraceptives and other fertility-control products,

contact NWRC at (970) 266-6000 or visit our Web site

at www.aphis.usda.gov/wildlifedamage/nwrc.

Wildlife Services Office Phone Numbers

For help with wildlife damage management issues

in your State, please call Wildlife Services’ toll-free

number at 1-866-4USDAWS (1-866-487-3297) or one

of the numbers listed below.

▘ NWRC Headquarters (Fort Collins, CO):

(970) 266-6000

▘ Eastern Regional Office (Raleigh, NC):

(919) 855-7000

▘ Western Regional Office (Fort Collins, CO):

(970) 494-7443

▘ Operational Support Staff (Riverdale, MD):

(301) 851-4009

“Solutions to problems depend upon

knowledge, which only research can provide.”

—Edwin R. Kalmbach, first Director for the

predecessor of the NWRC (1940–1954)

Solutions Through Science

Using Fertility Control To Manage

Wildlife Populations and Disease

Animal and Plant Health Inspection Service