Pennsylvanians can begin hunting deer with firearms when the season starts Monday.
But it's been open season the last few weeks for federal sharpshooters targeting the deer that for years have been overrunning Valley Forge and other national parks.
Since 2010, November has marked the start of the five-month "culling" season at the park. At Valley Forge National Historical Park, U.S. Department of Agriculture sharpshooters have killed more than 2,000 deer since the culling program started seven years ago, and about 170 deer are estimated to remain there. For the second year, park officials have met their goal of 31 to 35 deer per square mile.
The hunt was only supposed to last four years. Then National Park Service officials said they would rely on a nonlethal solution to maintain animal habitats — deer birth control.
Seven years later, that hasn't happened. Park officials maintain they will limit their hunting when an "acceptable" reproductive-control method emerges that meets their criteria. No fertility vaccine on the market checks every box.
Animal activists say current vaccines could work to control the deer population at Valley Forge, Gettysburg National Military Park, and other parks that hunt their deer.
Stephanie Boyles Griffin, a scientist who opposes the culling, accused officials of setting the bar too high "so that no fertility control agent will ever be acceptable for use" at Valley Forge.
"I don't think we should be kicking the can down the road and needlessly killing animals while we wait for the silver bullet," said Boyles Griffin, senior scientist in the wildlife protection department of the Humane Society of the United States and director of the Botstiber Institute for Wildlife Fertility Control in Media.
The longer a park uses hunting to control a deer population, the more wary deer become of people and the more difficult it is to shoot the animals with short-range vaccine dart guns, according to wildlife fertility control experts.
Fertility control methods in use now meet three of Valley Forge's four criteria: They don't require handling the deer, don't significantly change deer behavior, and don't leave hormonal residue in the meat, which the park donates to food banks.
Valley Forge also requires reproductive control to be 85 percent to 100 percent effective for three to five years. Vaccines available now generally last two to three years.
A deer contraceptive that lasts longer with one dose is likely years away, a point veterinarians made to park officials when they developed the criteria eight years ago. Researchers are testing a booster shot that would extend the potency of fertility vaccines to seven to eight years with a couple doses, said Allen Rutberg, director of the Center for Animals and Public Policy in the Cummings School of Veterinary Medicine at Tufts University in Massachusetts.
"It really should depend on whether it can control the population or not, rather than setting specific standards on how long it should last," he said.
Rutberg visited Valley Forge two decades ago and spoke with park officials about deer contraceptives. "At the time, it seemed feasible," he said.
Amy Ruhe, the park's natural resource manager, said setting a requirement for how long the vaccines must be effective minimizes the cost and labor for administering them to a large number of deer. The park spends between $97,000 and $173,000 of its $6 million annual budget on culling, the park service reported in 2015. Park officials estimated reproductive control would cost slightly more — $108,000 to $195,000 annually.
If the park does start to use a fertility control, officials still may use after-hours hunts to help maintain the deer population, Ruhe said.
Sharpshooters use bait to attract deer away from park boundaries, public roadways, and occupied buildings. They shoot the animals with non-lead bullets. In 2009, the park hosted about 240 deer per square mile. Now, fewer live in the entire 5½-square-mile park.
"It's been a very safe, effective, and humane operation," Ruhe said.
The park has donated more than 50,000 pounds of venison — more than 7,000 pounds last year. Forest habitats laid bare by too many deer are returning.