The Problem

Since the early 1900s, wildlife conservation efforts 

in the United States have focused on restoring, 

protecting, and managing populations of many 

wildlife species. In some cases, such as the whitetailed deer and Canada goose, these efforts have been 

so successful that these species have become locally 

overabundant. These and other overabundant species 

can cause a variety of conflicts with humans, ranging 

from minor nuisance issues to serious habitat and 

crop destruction, disease spread, and vehicle and 

aircraft collisions. 

Hunting and trapping have been the traditional 

methods fish and wildlife agencies use 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 

contraception is one method—when used as part 

of an integrated approach with other methods—that 

can potentially help manage locally overabundant 

wildlife populations in these particular settings. 

Science-Based Solutions

Scientists at the National Wildlife Research Center 

(NWRC), part of the U.S. Department of Agriculture’s 

(USDA) Animal and Plant Health Inspection Service 

(APHIS), are developing several wildlife contraceptives 

for use with overabundant mammal and bird species.

NWRC—the research arm of APHIS’ Wildlife 

Services program—works collaboratively with 

State fish and wildlife agencies, universities, zoos, 

international organizations, and private partners to 

develop, test, and register wildlife contraceptives 

for use in wildlife damage management. Some of 

the products investigated have been employed 

previously in human medicine or in farm animal 

production. Others have been dispensed as vaccines 

or as oral baits. Regardless of origin, contraceptives 

are a promising new wildlife management tool. 

Contraceptives alone, however, cannot rapidly reduce 

overabundant wildlife populations to healthy levels. 

Instead, they may be most useful in specific and 

limited situations in conjunction with other wildlife 

management methods, such as hunting. Immediate 

population goals can be met only by removing problem 

animals. Contraceptives can then be used to slow the 

rate of population recovery in these managed areas.

NWRC scientists strive to develop wildlife 

contraceptives 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 

GonaConTM-Immunocontraceptive Vaccine

Method of Application:

Single-shot, hand-injected vaccine 

Target Species:

Adult female white-tailed deer (Odocoileus virginianus)

GonaCon has been tested successfully in other 

mammal species, including elk, fallow deer, horses, 

bison, feral swine, prairie dogs, ground squirrels, and 

feral dogs and cats. Future registration of GonaCon for 

use in other species is expected.

How It Works:

GonaCon stimulates the production of antibodies that 

bind to GnRH—a gonadotropin-releasing hormone 

necessary for production of estrogen, progesterone, 

and testosterone. 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 present in the bloodstream, sexual activity is 

decreased, and vaccinated animals remain infertile. 

Effectiveness:

A single, hand-injected dose of GonaCon has 

successfully kept some female deer infertile for up to 

5 years in pen studies. During field studies in New 

Jersey and Maryland with free-ranging deer in semienclosed urban settings, the vaccine was 67 to 88 

percent effective at preventing pregnancy the first 

year and 47 to 48 percent effective the second year. 

A second dose can be administered during year 2 to 

extend contraceptive effectiveness. Additional research 

is needed to determine how often deer will need 

to be re-vaccinated to maintain infertility in 

subsequent years.

Status of Registration:

Registered by the U.S. Environmental Protection 

Agency (EPA).

Who Can Use:

GonaCon is regulated by EPA and is a restricteduse chemical. Only USDA Wildlife Services or 

State wildlife management agency personnel 

or individuals working under their authority can 

use it. GonaCon users must also follow State 

authorization processes. All requirements on 

the product label must be strictly followed.

OvoControl® G and P—Oral Bait

Method of Application:

Oral, bread-like bait fed to target animals prior to and 

during their breeding season; it can be distributed with 

broadcast bait feeders or by hand.

Target Species:

Resident Canada geese (Branta canadensis), 

Muscovy ducks (Anas moschata), and feral pigeons 

(Columba livia)

How It Works:

OvoControl contains 0.5 percent nicarbazin—the 

active ingredient traditionally given to broiler chickens 

to prevent the disease coccidiosis. A side effect of 

nicarbazin is decreased egg hatchability and egg 

production. Nicarbazin affects the hatchability of eggs 

by changing the pH of the yolk and weakening the yolk 

membrane, which allows the albumin and yolk to mix. 

It also inhibits sperm from fertilizing the egg. When 

OvoControl is fed to Canada geese or pigeons for the 

duration of their breeding season, it effectively reduces 

the hatchability of eggs. The effects are fully reversible, 

and when OvoControl is withdrawn, egg production and 

hatchability return to normal within a few weeks.

GonaCon is an injectable 

vaccine for use with 

mammals, such as whitetailed deer, prairie dogs, and 

feral dogs and cats.

Effectiveness:

OvoControl has no effect on the current number of 

adult or juvenile resident geese or pigeons. Under 

ideal conditions, with all target birds consuming the 

appropriate dose during the breeding season, no new 

chicks are hatched. Under actual field use, not all 

targeted birds may consume the bait. Consequently, 

some chicks may still be observed, although the 

numbers would be significantly reduced. Field studies 

in pigeons have shown a 50- to 55- percent reduction 

in flock population within 1 year.

Status of Registration: 

Registered by EPA.

OvoControl is a registered trademark of Innolytics, 

LLS, Rancho Santa Fe, California. NWRC scientists 

collaborated with Innolytics, LLC, for 8 years to develop 

the OvoControl products. In 2005, the EPA granted 

regulatory approval for the use of OvoControl to reduce 

overabundant resident Canada geese populations. 

A registration for feral pigeons and Muscovy ducks 

soon followed. 

Who Can Use: 

OvoControl is regulated by the EPA and is a restricteduse chemical. Only licensed wildlife specialists, USDA 

Wildlife Services, or pest management professionals 

are permitted to buy and use it. All requirements on 

the product label must be strictly followed.

DiazaCon–Oral Bait

Method of Application: 

Oral bait fed to target animals prior to their 

breeding season.

Target Species: Variety of birds and mammals with 

limited breeding seasons; current research involves 

monk parakeets, prairie dogs, and grey squirrels.

How It Works:

DiazaCon (20,25 diazacholesterol) is a drug originally 

developed to lower cholesterol in humans. It mimics 

cholesterol in the body, thus inhibiting the production 

of cholesterol and the formation of sex hormones 

necessary for reproduction. 

Effectiveness:

DiazaCon reduced nest productivity (nestlings 

plus eggs with embryos) of monk parakeets by 

approximately 70 percent. In preliminary studies in 

prairie dogs, DiazaCon reduced the number of prairie 

dog offspring born by approximately 98 percent. 

Status of Registration:

Not registered. Field studies in support of EPA 

registration are ongoing.

Who Can Use: 

DiazaCon will likely be registered as a “Restricted 

Use” agent and only be administered by licensed pest 

control operators, USDA Wildlife Services, or State 

wildlife management agency personnel or individuals 

working under their authority.

Overabundant feral 

pigeons and other 

wildlife can cause 

serious damage to 

natural habitats, 

agricultural crops, 

and urban landscapes.

The active ingredient (nicarbazin) in OvoControl® weakens the yolk 

membrane causing the yolk and albumin to mix.
More Information

For more information on the development of wildlife 

contraceptives, contact the NWRC at (970) 266-6000 

or visit our Web site at www.aphis.usda.gov/wildlife_

damage/nwrc.

Wildlife Services Office Phone Numbers

For assistance on 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.

At headquarters (Riverdale, MD): ▘ Operational Support Staff (301) 734-7921

In the field: ▘ NWRC Headquarters (Fort Collins, CO) 

(970) 266-6000

▘ Eastern Regional Office (Raleigh, NC) 

(919) 855-7200

▘ Western Regional Office (Fort Collins, CO) 

(970) 494-7443 

The U.S. Department of Agriculture (USDA) prohibits discrimination 

in all its programs and activities on the basis of race, color, national 

origin, age, disability, and where applicable, sex, marital status, 

familial status, parental status, religion, sexual orientation, genetic 

information, political beliefs, reprisal, or because all or part of an 

individual’s income is derived from any public assistance program. 

(Not all prohibited bases apply to all programs.) Persons with 

disabilities who require alternative means for communication of 

program information (Braille, large print, audiotape, etc.) should 

contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). 

To file a complaint of discrimination, write to USDA, Director, Office 

of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 

20250-9410, or call (800) 795-3272 (voice) or (202) 720-6382 

(TDD). USDA is an equal opportunity provider and employer. 

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 leaflet were taken by USDA 

employees or are part of the APHIS image collection.

Issued January 2010

www.aphis.usda.gov/wildlife_damage/nwrc

Safety of Contraceptives

The NWRC must adhere to Federal human 

health and environmental standards by registering 

chemicals, drugs, and vaccines with Federal and 

State regulatory agencies. The wildlife contraceptives NWRC develops are tested extensively and 

must meet or exceed the EPA’s rigorous safety 

standards. There are no known dangers associated with human or wildlife consumption of 

animals that have been treated with GonaCon or 

OvoControl. Secondary hazard studies are ongoing 

for DiazaCon.

Future Research

Future NWRC research on wildlife contraception will 

likely involve studies to support expanded registration 

of existing products, develop oral delivery systems, 

and prevent transmission of wildlife diseases. Potential 

research areas include the following: ▘ Development of new formulations and delivery 

methods, including automated vaccine delivery 

systems for administering the injectable form of 

the GonaCon vaccine, as well as oral and nasal 

delivery systems. 

▘ Prevention of the spread of brucellosis in bison. 

Brucellosis is a bacterial disease that causes 

infertility, abortions, and lowered milk production 

When OvoControl

® is withdrawn from the diet, hatching success 

and egg production return to normal within a few weeks.

in cattle and bison. The disease is transmitted 

through contact with bodily fluids, such as milk 

and after-birth tissues, of infected animals. 

GonaCon could potentially break the cycle of this 

disease and reduce transmission by preventing 

reproduction in infected animals.

▘ Combined rabies and GonaCon vaccine for 

reducing stray dog populations and rabies in 

developing countries.

About Wildlife Services’ National Wildlife 

Research Center

NWRC is the only Federal research facility in the 

United States devoted entirely to the development of 

methods for effective wildlife damage management. 

The Center applies scientific expertise to address 

human-wildlife conflicts involving a complex 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 throughout the 

United States and abroad. Often, the Wildlife Services’ 

operational personnel assist NWRC scientists in 

developing and evaluating 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 a wide range of 

disciplines, including animal behavior, wildlife biology, 

wildlife sensory biology, chemistry, reproductive 

physiology, immunology, epidemiology, statistics, 

population modeling, genetics, toxicology, and 

veterinary medicine. 

“Solutions to problems depend upon 

knowledge, which only research can provide.” 

—Edwin R. Kalmbach, first Director for the 

predecessor of the NWRC (1940–54)

United States Department of Agriculture

Animal and Plant Health Inspection Service 

Miscellaneous Publication No. 2035

Solutions Through Science

Wildlife Contraceptives