Taking a shot at deer contraception

October 08, 2006|By CANDUS THOMSON

Silver Spring — Silver Spring-- --Doe No. 8 is a party animal.

With acres to graze, she's looking fat and sassy. In each ear, hanging like flashy earrings, are orange tags with her number. It's almost breeding season and the bucks aren't far away.

But thanks to a dart in her rump two years ago, Doe No. 8 - like her running mate, Doe No. 14 - is more than likely to be practicing safe sex this year.

Biologists are using the fenced-in campus of the Federal Research Center at White Oak, just outside the Capital Beltway, to see if a new contraceptive can keep a white-tailed deer herd in check. A similar study is being conducted in New Jersey.

Using revenue from hunting license sales, the Department of Natural Resources is helping pay for the study, and the General Services Administration is providing the site for the field work.

With hunters doing their part to rein in Maryland's deer population in the wild, it's becoming critical for wildlife managers to find ways to control burgeoning numbers in the suburbs, where arrows and gunfire aren't appropriate.

Deer contraception is always offered as a "silver bullet," when wildlife and suburbia collide. Most recently, it was raised when DNR announced a managed archery hunt to thin the herd at Soldiers Delight Natural Environment Area near Liberty Reservoir.

People who hike or walk their dogs at Soldiers Delight, which is not a park under the state's definition, worried about stray arrows and asked if deer could be darted with birth control drugs instead.

Using GonaCon (short for gonadotropin, which can prevent a doe from going into heat and a buck from producing sperm), isn't easy, isn't cheap and won't be approved by the Environmental Protection Agency until late next year at the earliest.

"You need a small, controlled area, two or three square miles," says Kevin Sullivan, the U.S. Department of Agriculture biologist who conducted the Silver Spring study. "You won't be able to dart and vaccinate enough animals in a wide-open space to make a difference."

Sullivan and his keen-eyed assistant, Scott Healey, know almost every inch of the mile-square area where 100 deer live. They track the deer with radio telemetry. Still, keeping up with their test animals can be trying.

"You need to be within 30 yards to shoot. Even here, we can drive around all day and only dart four deer," says Sullivan.

And there's one other thing about GonaCon: Biologists say it will never replace hunting as a 100 percent effective management option.

But places like this rolling-green campus and the fenced-in National Institute of Standards and Technology compound in Gaithersburg are perfect candidates for GonaCon.

NIST began its deer contraception program a decade ago, when its resident herd was about 300 animals. After fits and starts, the program took hold, and the federal agency says the population is now fairly stable at about 200.

That pilot program, however, was labor-intensive because the PZP vaccine lasts only a year and requires an initial injection and booster shot before the fall rut.

Scientists from the National Wildlife Research Center in Fort Collins, Colo., developed GonaCon.

To pave the way for the study, the Silver Spring herd was thinned by 214 deer in October 2003. The next summer, biologists captured 28 does, vaccinated them with GonaCon, tagged their ears and fitted them with radio collars. Fifteen does were not vaccinated to provide a control group.

Doe No. 8 and Doe No. 14 were in that first batch of vaccinated critters. The fall mating season came and went. The next spring neither deer gave birth. Only 12 percent of the vaccinated does did.

Mating season arrived last year as the leaves turned and fell. Although No. 8 and No. 14 remained fawn-free, the failure rate among the other vaccinated deer fell to 50 percent.

Sullivan suspects that an early batch of GonaCon lost its effectiveness. A new one, he believes, will prove more potent.

"Numbers 8 and 14 will be key this next year. If the vaccine works in years three and four, we'll have a breakthrough," he says. "If you dart a 2-year-old doe and the vaccine lasts four years, you're talking about shutting down a doe for its reproductive life span."

With the two-year study drawing to a close, DNR and Sullivan are beginning another round of tests. Another 30 deer will be darted between now and late November and biologists will see what happens next spring.

Deer control in suburbia comes with a price. Hunters work for free, and actually generate revenue through license and ammunition sales. Professional sharpshooters can cost $100 to $300 per deer. The cost to dart a deer runs from $800 to $1,000.

Paul Peditto, the head of DNR's Wildlife and Heritage Service, says even if only 30 percent of the does in a given area still are having offspring, that's more than enough to keep a herd growing.

"Even if it was 100 percent effective, immunizing every deer is a slow, costly way to manage the population," Peditto says. "It's not pixie dust that can be applied everywhere. It's a tool we look forward to using, but it will never replace hunting, and it will be limited to circumstances where hunting will not work."


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