'Fertility control' can help manage wildlife

The debate over how to manage deer in Valley Forge National Historical Park is similar to discussions taking place in communities across the nation. The growth of cities and suburbs limits forest habitat and forces communities to cope with "urban deer," which pose a hazard for motorists and pedestrians and destroy gardens and flower beds.

There are many opinions on what to do about these animals, but no easy answers. Finding solutions is made harder because wildlife management is an emotional issue for many.

As a scientist who has devoted his career to wildlife management via fertility control, I'm often frustrated that the debate so often focuses on the either/or proposition of "culling the herd," i.e. killing animals to reduce their numbers. An alternative is controlling animal fertility, which can be done via several methods, including vaccines that prevent reproduction, drugs that control hormonal regulation, and surgical sterilization.

Fertility control may not always be the best solution. It can depend on a variety of factors, including habitat and the species in question. But it's an option that should be weighed and discussed in an informed manner.

When wildlife managers and community leaders do mention fertility control, they often impart outdated or inaccurate information. They seem out of touch with the last 30 years of scientific study that demonstrates the reliability and effectiveness of the approach.

In the coverage of the Valley Forge deer story, for example, a community official stated that fertility control is "not yet a viable option," and could pose a risk to human health if used. Neither statement is accurate.

Time magazine, in a cover story about human-wildlife interactions titled "America's Pest Problem," stated that fertility control "works only in captive populations." That's also not true.

The truth is, fertility control has worked - and continues to work - in numerous situations and locations around the globe. One long-running example is in the Assateague Island National Seashore in Maryland, where National Park Service managers have used fertility vaccine to manage a wild horse herd for more than 25 years. The same vaccine is also used in 20 other horse management areas for the Park Service, Bureau of Land Management, and other agencies.

Fertility vaccine has also been used for 15 years to manage elephants living in more than a dozen wildlife reserves in South Africa. And, recently, the successful use of fertility vaccine to control the wild bison herd on Catalina Island in California has attracted worldwide media attention.

Fertility vaccine also works in deer. Research by Tufts University scientists and others performed in three locations - Fire Island National Seashore in New York, the campus of the National Institute of Standards and Technology in Maryland, and Fripp Island in North Carolina - led to reductions in urban deer populations by 30 to 60 percent. The findings were published in Wildlife Research and the Journal of Zoo Wildlife Medicine by Allen Rutberg and colleagues.

Research has shown fertility vaccine works in more than 85 species, including bears, giraffes, and water buffalo. It can be delivered via small darts fired from a CO2-powered rifle. There is very little risk of injury to animals during darting and no short- or long-term health hazards. The vaccine doesn't harm animals that are already pregnant or their offspring. And the vaccine cannot pass from one animal to another, to humans, or into the environment. It is digested in the animal's gut and doesn't remain in the feces.

Perhaps most significantly, the effects of the vaccine are not permanent. Once it wears off, usually after two years in most species, the vaccinated animal becomes fertile again. This provides great flexibility in wildlife management scenarios - unlike surgical sterilization or culling.

While the time and cost of vaccinating animals may be an issue in some situations, it can offer significant savings in others. For example, the U.S. Department of the Interior currently spends more than $70 million each year to round up and care for wild horses in regions where vaccination isn't used. The cost of managing herds via vaccination at $25 per dose is significantly less.

While wildlife managers may choose to use a different approach than fertility control, they should review the scientific literature and consider the pros and cons, as should community members. Communities make the best decisions when they consider all the information in an informed way.