Frequently Asked Questions 2017-12-12T17:16:10+00:00


Information is the first step toward implementation of wildlife fertility control

What is wildlife fertility control? 2017-10-13T13:40:14+00:00

A nonlethal method of population management which focuses on reducing the birth rates of wildlife rather than increasing the mortality rates.1

How long has fertility control for wildlife been studied? 2017-10-13T13:42:57+00:00

The study of wildlife contraception dates to the 1960s when synthetic steroids were being investigated for their contraceptive use.2 Surgical contraception research has been ongoing since the 1970s.17 During the mid-1980s research into the use of immunocontraception emerged.3

What are the current types of wildlife fertility control? 2017-10-19T13:54:21+00:00

Contraceptive methods for wildlife management include fertility inhibitors such as Nicarbazin, surgical, hormonal, and immunocontraception.4 15

What is Nicarbazin? 2017-10-13T13:46:38+00:00

Nicarbazin is a compound that causes a reduction in hatchability and egg laying due to increased membrane permeability between the egg white and egg yolk.2 This oral fertility inhibitor is reversible and is cleared from the body after 48 hours.1

What does surgical sterilization entail? 2017-10-13T13:48:26+00:00

Surgical methods of contraception include tubal ligation, tubal transection, ovariohysterectomy, ovariectomy, gonadectomy, vasectomy and salpingectomy. While most of these procedures are permanent, tubal litigation is reversible.5 15 18

What are hormonal methods of immunocontraception? 2017-10-13T13:50:02+00:00

Hormonal methods of contraception include progestins, which disrupt reproductive processes in males and females.16 There are oral progestins as well as depot injections containing progestin that regulate contraception. Deslorein implants are an example of a GnRH-agonists which have been used on captive wildlife to inhibit reproduction.15

What does an immunocontraceptive vaccine do? 2017-10-13T13:51:06+00:00

An immunocontraceptive vaccine induces antibodies against proteins or hormones essential for reproduction.14

What are examples of immunocontraceptives? 2017-10-13T13:52:09+00:00

Porcine zona pellucida (PZP) vaccine and gonadotropin-releasing hormones (GnRH) vaccine are both examples of immunocontraceptive vaccines.1

How are immunocontraceptives administered? 2017-10-13T13:56:55+00:00

These vaccines are injected Intramuscularly via syringe-darts shot by dart rifles or injected by hand. They can also be injected using bio-bullets.4

Can you eat animals treated with PZP? 2017-10-13T13:57:54+00:00

Yes, PZP and GnRH-based vaccines are digested like any other protein, so they never enter the food chain; they do not pose a risk to predators or humans.4 13

Why are females typically targeted? 2017-10-13T13:59:36+00:00

Fertility control focuses on females because many mammal species are polygynous or polyandrous. If males were targeted there would need to be a very high percentage of male sterility to have population-level effects.4

Can pregnant or juvenile animals be treated with immunocontraceptives? 2017-10-13T14:02:08+00:00

Both are safe; GonaConTM (a GnRH vaccine) given to 3-4-month-old fawns did not contracept nor prevent sexual development. GonaConTM was also given to pregnant bison and it did not affect the pregnancy.4 PZP was found safe to be given to pregnant or lactating females as well.4

Who regulates fertility control products? 2017-10-13T14:04:21+00:00

The Environmental Protection Agency regulates products in the United States, but each individual state has the authority to control the use of fertility control products. In Australia, the Australian Pesticide and Veterinary Medicine Authority. The European Union Directives regulates products in Europe, as well as by each individual member country. The Environmental Risk Management Agency/Food Safety Authority regulates products in New Zealand.6

Are there any immunocontraceptives registered for use in the U.S.? 2017-10-13T14:07:03+00:00

Ovocontrol® was registered by Innolytics LLC as a reproductive inhibitor for use in Canada geese in 2005 and for use in pigeons in 2007.1

GonaConTM was registered in 2010 for use with white-tailed deer, feral horses, and feral donkeys.4

ZonaStat-H was registered by The HSUS in 2012 as vaccine for horses and wild burros.7

ContraPest was registered in 2016 by SenesTech, Inc. as an oral fertility inhibitor for Norway Rats and Roof Rats.8

ZonaStat-D was registered by The HSUS in 2017 as a vaccine for white-tailed deer.9

Internationally, what immunocontraceptives are available for use? 2017-10-13T14:10:16+00:00

Ovistop was registered in Italy by Acme Drugs as a as a fertility inhibitor for pigeon control.10

SpayVac® is registered in Canada by Immunovaccine Technologies, Inc. as a vaccine for animal contraception.11 19

Improvac® was registered in South Africa as a GnRH vaccine for pigs in 2006.15

Where has fertility control been used to manage wildlife populations? 2017-10-19T13:38:18+00:00

African elephant populations in more than 25 game preserves in South Africa, including the Greater Makalali Private Game Reserve, are presently being managed with PZP.3 PZP is also used to manage wild horse populations on public, private and tribal lands, military bases, national parks, barrier islands, and U.S. Territories, such as Puerto Rico.12 Pigeons are managed with nicarbazin-based products worldwide in places like Barcelona, Spain and Singapore, as well as manufacturing facilities, such as oil refineries, chemical plants, and power stations, hotels and casinos, university campuses, shopping centers, health care facilities, and apartment and condominium complexes.20, 21 ContraPest has been field tested in New York City’s subway stations, North Carolina agricultural farms, and Indonesian rice farms; New York City and Chicago have both launched a pilot project to test the product in 2017.22


1 Fagerstone, K. A., Miller, L. A., Killian, G., & Yoder, C. A. (2010). Review of issues concerning the use of reproductive inhibitors, with particular emphasis on resolving human-wildlife conflicts in North America. Integrative Zoology,1: 15-30. doi:10.1111/j.1749-4877.2010.00185.x

2 Fagerstone, K.A. (2002) Wildlife fertility control. The Wildlife Society

3 Delsink, A., Kirkpatrick, J., Berkschinger, H., Van Altena, J., Telecky, T., & Rowan, A. (2012). Free-ranging African Elephant Immunocontraception: a new paradigm for elephant management (Rep.)

4 Massei, G., & Cowan, D. (2014). Fertility control to mitigate human–wildlife conflicts: a review. Wildlife Research, 41(1). doi:10.1071/wr13141

5 Boulanger, J. R., & Curtis, P. D. (2016). Efficacy of surgical sterilization for managing overabundant suburban white-tailed deer. Wildlife Society Bulletin, 40(4), 727-735. doi:10.1002/wsb.706

6 Humphrys, S., & Lapidge, S. J. (2008). Delivering and registering species-tailored oral antifertility products: a review. Wildlife Research, 35(6). doi:10.1071/wr07145

7 EPA. (2012). Pesticide Factsheet: Porcine zona pellucida (United States, The Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention). Original article

8 EPA. (2016). Notice of pesticide registration: contrapest (United States, The Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention). Original article

9 EPA. (2017). Label Amendment – Adding sublabel B for deer (United States, The Environmental Protection Agency, Office of Chemical Safety and Pollution Prevention) Original article

10 Ovistop International. (2016). What is it? Retrieved from

11 Government of Canada. (2017). Canadian Trademarks Details: 1087041 – SPAYVAC. Original article

12 Masters, B. (2017). Can Fertility Control Keep Wild Horse Herds in Check? Original article

13 APHIS. (2007). GonaConTM —Birth Control for Deer: Questions and Answers (United States, United States Department of Agriculture, Animal and Plant Health Inspection Service). Original article

14 Massei, G. (2017, July 18). An overview of fertility control to mitigate human-wildlife conflicts in an overcrowded world. Lecture presented at 8th International Conference on Wildlife Fertility Control, Washington D.C.

15 Bertschinger, H. and Caldwell, P. (2016), Fertility suppression of some wildlife species in southern Africa—a review. Reproduction in Domestic Animals, 51: 18–24. doi:10.1111/rda.12783

16 Massei, G., Cowan, D., & Eckerly, D. (2014). Chapter 10: Novel Management Methods: Immunocontraception and Other Fertility Control Tools. In Behaviour and Management of European Ungulates, ed. Rory Putman and Marco Apolloni (pp. 209-235). Dunbeath, Scotland: Whittles Publishing

17 Kennelly, J. J., & Converse, K. A. (1997). Surgical Sterilization: An underutilized procedure for evaluating the merits of induced sterility. Contraception in Wildlife Management, 21-28.

18 George K, Kamath MS, Tharyan P. (2013). Minimally invasive versus open surgery for reversal of tubal sterilization. Cochrane Database of Systematic Reviews, Issue 2. Art. No.: CD009174. DOI: 10.1002/14651858.CD009174.pub2.

19 Meeusen, E. N., Walker, J., Peters, A., Pastoret, P., & Jungersens, G. (2007). Current Status of Veterinary Vaccines. Clinical Microbiology Reviews, 20(3), 489-510. doi:10.1128/CMR.00005-07

20 Putnam, L. (2016, November 27). Pigeons in Spain are going on birth control. Original article

21 Boh, S. (2016, November 09). Pigeon number at Palmer Road drops after ‘birth control’ trial. Original article

22 Vivanco, L. (2017, July 25). Chicago adds rat birth control to rodent-fighting arsenal. Original article