Protesters approach a car during a demonstration in Canton, Mass., against a deer hunt. A plan to allow hunting to cull an exploding deer population is under fire from activists who want other methods used.

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

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, according to state wildlife biologists. 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 Department of Conservation and Recreation.

Ninety-eight hunters, armed only with shotguns, will be allowed in the reservation for each two-day hunting session — Nov. 30 and Dec. 1, and Dec. 7-8 — and 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, which state officials acknowledge 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.”

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

Animal welfare groups say the state didn’t properly consider 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, 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.