Marshlands' Problematic Deer Population Subject of Research Study

If you live in Greenhaven, chances are you've gotten something in the mail from fellow Rye resident Hank Birdsall.

Birdsall, a biology major at Purchase College, is conducting a survey for his senior thesis on the white-tailed deer population in the Marshlands Conservancy. As part of the study, he's asking Greenhaven residents to share with him the extent to which they've observed deer activity in the neighborhood.

Birdsall, who calls the deer overpopulation "a detriment to both people and the local eco-system," estimates that there are currently between 45-65 deer on the county-owned 173-acre property. He's studying "the relationship between the wild cover areas and the suburban lawns where they feed and most often come in contact with humans."

Birdsall has put up cameras on the periphery of the Marshlands property and has mailed out nearly 200 questionnaires since January in order to assess the extent to which the deer have proven problematic for Greenhaven residents.

The deer population has surged in recent years and has consequently disrupted the ecological balance of Marshlands. Birdsall said that the main problem is that the deer don't have any natural predators.

"In nature everything operates in a cycle. The deer are supposed to be checked by predators. Without that check on the deer population, they've been able to proliferate," Birdsall said.

Areas in upstate New York most often control deer populations by allowing hunting, but last year the Westchester Department of Parks, Conservation, and Recreation only permitted bow-hunting in two Somers parks from October 17 through December 31.

According to the Westchester County Citizen's Task Force on White-Tail Deer and Forest Regeneration, this year's hunting season regulations are currently being planned.

Coyotes are an obvious natural predator to deer, but are only physically capable of taking down fawns, according to Birdsall. The coyotes have turned to other forms of prey though, namely domesticated animals.

For Greenhaven Rye Association President Marie McKeige, the surplus of deer and coyotes making their way into the neighborhood have caused major problems.

McKeige now maintains a fenced-in garden in her backyard after deer began eating the plants in her front garden. But the problem goes far beyond that. 

When driving at night, McKeige said that at least twice a week she "runs into deer on the street and they don't care to move."

McKeige also said that other residents have even seen deer get seriously injured while attempting to leap over fences. Some even end up dying in backyards.

For residents' pets, the situation can also be deadly. Due to the influx of coyotes, "small cats and small dogs have gone missing from our neighborhood lately," McKeige said.

Christopher Graseck, President of Friends of Marshlands, told Patch that the deer overpopulation is problematic within the borders of the Marshlands property as well.

Because deer graze on native plants and avoid invasive species like the multi-floral rose, Graseck said the deer "make it very difficult to do any habitat restoration." If the county were to remove the invasives and reintroduce more native species, the deer would quickly devour the plants and consequently leave the property again vulnerable to invasives.

Birdsall noted that forest regeneration is virtually impossible when there's a  deer overpopulation: "Forest regeneration occurs at a healthy rate when there's 10 deer per square mile. When there's 60 deer per square mile, you don't get forest regeneration."

While the results of Birdsall's research won't be completed until December, he hopes that his conclusions will be an important part of developing an effective deer management strategy in the future.

"A lot of people have very strong opinions on deer and if a management decision is going to be made, I hope my research will help support it," he said.

Hank Birdsall's research study on the white-tailed deer population in the Marshlands Conservancy is ongoing. He's requesting that Rye residents let him know of any deer activity they may have observed. Please email him at hank.birdsall@gmail.com.