A plan to allow hunting in a nearly 11-square-mile swath of pristine forest within sight of downtown Boston, in order to thin an exploding deer population, is coming under fire from activists who say contraception and other more humane methods be used.

According to state wildlife biologists, the hunt in the Blue Hills reservation is needed to trim a deer population estimated at 85 animals per square mile, far above the ideal of six to 18 deer per square mile. Hunting has not been allowed in the park since the state set it aside for public recreational use in 1893.

The deer are a threat to public safety and a threat to the forest ecosystem, said Matthew Sisk, deputy commissioner of the state department of conservation and Recreation (DCR), which oversees the park that is popular with hikers, mountain bikers and cross country skiers.

Ninety-eight hunters, armed only with shotguns, will be allowed into the reservation for each two-day hunting session – 30 November to 1 December and 7 December to 8 December – but only about 3,000 of the reservation’s 7,000 acres will be open to them. Hunters will be allowed to take up to six deer, and the goal is to get down to the ecologically stable level of fewer than 20 deer per square mile. State officials acknowledge that may not be reached this year.

“The problem that is most vexing to me is forest health,” Sisk said. “You can see 250 to 300 yards into the woods, and that is not healthy. The deer are eating the under-canopy of the forest.” That, in turn, threatens other wildlife and plant species, he said.

There have been increased reports of vehicles striking deer in recent years, and under current conditions the forest is more prone to fires, Sisk said, which could threaten homes in the densely populated suburbs that surround the reservation.

Animal welfare groups say the state has not properly considered non-lethal methods to control the deer population.

“Contraception is a humane, long-lasting approach to population control and we believe this approach should be prioritized,” said Laura Hagen, deputy director of advocacy at the MSPCA’s Angell animal medical center in Boston.

Contraception and sterilization were considered by the state, but the science behind those methods is still developing and they were determined to be too expensive, Sisk said.

“A hunt is a very effective, low-cost way of culling a herd,” he said.

Allen Rutberg, director of the Center for Animals and Public Policy at Tufts University’s Cummings School of Veterinary Medicine, said deer contraception programs in other areas of the country have worked.

But Rutberg, who stresses that he has no official position on the best way to control deer in the Blue Hills, acknowledges that such programs are labor intensive and expensive. The contraceptive is delivered to does as an injection.

“You have to be able to reach enough animals to treat them,” he said.

The state’s reasoning does not wash with Rob Morrissey of Braintree, who hikes in the reservation every day and is a member of a group called Friends of the Blue Hills Deer.

“A lot of people don’t like to see the animals killed,” he said. “I think it’s worth the extra cost to have a more humane way to control the deer population.”

Friends of the Blue Hills Deer is not affiliated with Friends of the Blue Hills, a non-profit that works with the state to preserve and protect the reservation. The latter organization agrees that the deer herd needs to be thinned, but has no official stance on a method to do so, executive director Judy Jacobs said.

“We trust DCR – they have done the research and they have the expertise,” she said.

Morrissey questions the state’s deer population numbers.

“The DCR’s numbers are based on a 2013 survey, and we’ve had two very harsh winters since then,” he said. “I have not seen a single deer this year – plenty of deer skeletons, but no deer.”

He is also worried about hunting accidents and entrails left behind when deer are field dressed.

“Four hundred sets of deer guts in the woods? Families don’t want to see that,” he said.