The deer departed

And the ones that will remain while the National Park Service conducts a controversial mammal birth-control experiment at Point Reyes National Seashore

  • Fallow deer outside the Bear Valley Visitor Center at the Point Reyes National Seashore

  • Deer use their antlers to scrape away ground vegetation, break tree limbs and girdle trees

  • A fallow deer buck with vegetation caught in its antlers

    US Geological Survey

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To mollify the activists, the Park Service settled on a scheme that involves shooting mostly stags. Many of the exotic does will be kept alive so park officials can exercise a “humane alternative” — capturing females with nets dropped from helicopters and injecting them with a contraceptive drug.

The experiment will employ GonaCon, a mammal contraceptive developed by the National Wildlife Research Center, a USDA pharmaceutical lab in Fort Collins, Colo. The center develops contraceptives and poisons designed to reduce pest populations where hunting is either impractical or impolitic. GonaCon keeps deer infertile — but only if they’re frequently re-injected.

At Point Reyes, this means that some 1,100 does that wander through more than 100 square miles of parkland must be found, captured and injected once a year over the course of the experiment’s 20-year lifespan. The contraception program will cost the park $210,000 per year.

And because of the difficulties of finding and re-injecting the does on schedule, park officials concede the deer birth-control effort is unlikely to work. “The contraceptive would not be a practical tool for trying to eliminate a population, because it’s not always 100 percent effective,” said Gail Keirn, spokeswoman for the National Wildlife Research Center.

“It may or may not work here,” adds Gates, the seashore biologist. “But it may have applications across the country.”


Over the past two decades, Kirkpatrick and his Science and Conservation Center have tested his version of a mammal contraceptive, PZP, on wild horses and deer. During experiments over many years, he’s found the injected serum can stanch mammal population growth under certain conditions.

But like GonaCon, the Agriculture Department’s birth-control vaccine, PZP has limitations that will be familiar to hairless bipedal mammals who’ve had to remember to take birth control pills. At their current level of development, deer contraceptives require repeated injection, making them impractical for all but the smallest, most-confined and tamest deer populations: those trapped in cities and suburbs.

Although deer contraception has almost no potential to supplant hunting as a method for checking wild deer populations, during Kirkpatrick’s decades of vaccine testing, he says he’s encountered strong opposition from hunters’ groups and state fish and game departments. And Allen Rutberg, assistant professor at the Center for Animals and Public Policy at the Cummings School of Veterinary Medicine at Tufts University, says the idea that deer contraception is a threat to hunting has become a self-sustaining legend.

“Expectations for contraception are wildly inflated on both sides,” Rutberg says. “There are (animal rights) advocates who say that contraception will be the end of hunting, and I have heard that lots of times. There are also (wildlife) agency folks who see this as a threat to hunting; they are nervous about it because of what the animal-rights people say.”

Deer overpopulation is a growing problem in the West and across the country, as cities expand into deer habitat. In February, Coeur d’Alene, Idaho, city council members planned to meet with the state Fish and Game department to address a local deer plague. In April, Helena, Mont., announced a new city wildlife management plan to fend off a growing urban deer population. In Texas, New Mexico and Arizona, among other states, whitetail and other deer species are thriving in the open spaces of suburbia.

Deer contraception has been shown to work on isolated populations — at Fire Island, N.Y., and at the National Institute of Standards and Technology campus in Gaithersburg, Md., for instance — and it has legitimate use controlling tame deer living in cities. But the seemingly innocuous blocking of reproduction by a small number of suburban does will likely continue to face resistance, Kirkpatrick says, thanks to an irrelevant debate over sport hunting.

By caving into pressure and using deer contraception in an environment it wasn’t intended for, the National Park Service risks simultaneously encouraging animal-rights activists’ vain hopes and hunters’ unwarranted fears that deer contraception will be used to limit sport hunting in America.

“I’ve hunted everything over the course of my life: pheasants, deer, elk, antelope. That’s why I believe this whole issue of connecting this (contraceptive) to hunting is irrational,” Kirkpatrick, the deer-contraceptive researcher, says. “I can’t begin to connect the idea of sport hunting to shooting human-habituated deer.”

The author writes from California.

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