Oh Deer!- page 1 | Science | Smithsonian

Oh Deer!

Contraception shows promise, but other measures may be needed to lessen the toll that the deer boom is having on forests and suburbs

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"Put your chest on the deer. Reach out and hold the legs. Never let go of the hooves."

Bill McShea, a wildlife biologist at the National Zoo in Washington, D.C., is instructing a handful of assistants in the art of subduing a wild white-tailed deer. The researchers are in Virginia's Blue Ridge Mountains on a warm morning, the mowed grass along the boundary of the woods still gleaming with dew. The night before, the group had sprinkled a trail of alfalfa pellets into five deer traps, wooden boxes about five feet tall with doors that fall shut when a deer steps inside and trips a string. This animal went for the bait.

"It's a feisty one," an assistant says, listening to the thumping hooves.

McShea and co-workers guide the deer through a door in the trap into a smaller box, then pull the squirming nearly 100-pound animal out by its hind legs. Two people pin it to the ground, and each grabs a set of kicking legs. Another helper covers its eyes with a dark towel. "That'll take 90 percent of the fight out of the deer," says McShea. The animal is female, so McShea reaches for a syringe and injects her in the rump.

The syringe contains an experimental contraceptive drug. McShea and others are testing, first, whether it will reliably block a doe's reproductive cycle for life and, second, whether birth control drugs could possibly make a dent in America's deer population boom. When it comes to controlling deer populations, McShea says, "You want to have as many tools as possible."

Once overhunted, white-tailed deer have returned in such explosive numbers that they're ravaging forestland and besieging rural and even suburban communities. The animals cause car accidents, carry ticks that can transmit infectious diseases to people, chew up landscaping and otherwise make pests of themselves, albeit sometimes strikingly graceful ones.

Deer numbers are rising in part because their traditional predators, including mountain lions and gray wolves, were eliminated from most Eastern forests long ago. Also, white-tailed deer reproduce quickly—a female bears one to three fawns each year—and they're one of the more adaptable species around, living from subarctic to tropical climates. Past restrictions on deer hunting have also fueled the boom.

But deer are also thriving because of the ways people have carved up the countryside, unwittingly creating prime deer habitat. Deer, says McShea, are an "edge species," meaning they thrive where forests meet fields. They seek shelter in forests, but most forest food is too high for them to reach. Edges abound in plants deer can munch. "Originally, the eastern United States was one deep, dark forest," McShea says. "Now it's deer nirvana. It's one big edge."

In some parts of highly suburbanized New Jersey, up to 60 deer live in a square mile, according to the state's Division of Fish and Wildlife, compared with just 5 to 10 deer per square mile before the land was settled by Europeans.

With so many deer at large, interactions are common. Nationwide, cars hit at least 1.5 million deer a year, the Insurance Institute for Highway Safety reports, causing more than a billion dollars in vehicle damage. In 2003, collisions with animals killed 210 people, and three-quarters of the encounters involved deer. Deer transport ticks that carry Lyme disease; more than 21,000 cases were reported in 2003.

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