Federal court rules deer culling, fencing allowed at Fire Island's Sunken Forest

For decades local ecologists have watched with concern as Fire Island’s burgeoning deer populations consumed native understory plants, threatening the health of the Sunken Forest Preserve’s delicate landscape.

A federal-court decision Friday allowed the National Park Service, which oversees Fire Island’s protected lands, to proceed with a plan to fence off large parts of the Sunken Forest Preserve and to continue to cull the area’s deer, which professional sharpshooters have been doing on Fire Island every winter since 2020.

In a 2-1 decision, the U.S. Court of Appeals for the Second Circuit found that despite deed restrictions, the federal agency could take measures to control the deer. A lawsuit filed by the New Jersey-based conservation group Wildlife Preserves, which had helped preserve the land, had argued the federal efforts had violated conditions of the donation, which prevents activities "that would adversely affect either the flora or the fauna."

Since deer were threatening to harm the forest’s flora and fauna, the court said, it was reasonable to restrict their access to the area, and to reduce their numbers.

"The government may take some adverse steps against a single species for the net benefit of the wider ecosystem," Circuit Judge Alison Nathan wrote in her opinion.

The National Park Service was not available for comment Tuesday, according to a spokesperson. The Wildlife Preserves did not reply to a request for comment by press time.

The Sunken Forest, so called because it grows behind the protective barrier of higher dunes, is a highly rare ecosystem of broadleaf hollies — some of which are thought to be at least 300 years old — as well as shadbush, sassafras, oaks and black cherries.

In the 1960s deer were a rare sight on Fire Island, and an aerial survey in 1971 counted just 46 deer. Today, the park service estimates between 300 and 500 deer inhabit the island, which is smaller than 10 square miles.

Twenty years ago a research wildlife biologist from the U.S. Geological Survey noted that the animals had devoured much of the herb layer — the soft stemmed plants growing low to the ground — as well as tree saplings in the forest. When test plots in the Sunken Forest were fenced off in the 1980s to keep deer out, the results seemed to confirm that the reduction in shrub species such as inkberry and huckleberry could be blamed on deer. "By the second growing season," wildlife biologist H. Brian Underwood wrote, "herb cover inside the deer exclosures increased by about 50%."

The overbrowsing left birds, small mammals, reptiles and insects with less to eat, and ground-nesting birds had less habitat in which to raise their young.

In 2017, the park service finalized a program to remove deer from the Sunken Forest, which would allow the overbrowsed understory to regenerate. The plan was to fence off 29 acres of the preserve, along with another 15 acres farther east, with tall mesh fencing that would exclude deer but let small animals pass through. As the fencing went up, deer would be shooed out. Any that remained in the exclusion zone would be culled by professional sharpshooters or captured and euthanized.

The park service’s deer management plan noted that attempts in the 1990s and 2000s to reduce populations through fertility control were not consistently successful.

The goal was to reduce the numbers of deer to 20 to 25 deer per square mile in the National Seashore, and none in the fenced Sunken Forest. By the park service's most recent population estimate, which varies year to year, the density would be roughly double that.

Soon after the fencing work began, a land conservation group sued to stop it. The group, Wildlife Preserves, had raised funds along with The Nature Conservancy in the 1950s to acquire the land, and form the Sunken Forest Preserve which was donated in 1966 to the newly established Fire Island National Seashore.

There were caveats: The agreement specified that the land was to be preserved "in as nearly its present state as possible" and that "hunting, trapping, fishing" were prohibited. If any activities were permitted "that would adversely affect either the flora or the fauna," the agreement was voided and ownership of the land would revert to the donor.

Wildlife Preserves didn’t deny that deer were damaging the forest but argued in its lawsuit that the government’s plan to cull them violated the ban on hunting.

Circuit Judge Myrna Peréz agreed, writing in a dissenting opinion that according to the majority decision, "the deed prohibits hunting or trapping a white-tailed deer but not sharpshooting or euthanizing one. That doesn’t make sense."