Solving Staten Island’s Deer Problem With a Snip and a Stitch
New York Times, September 22nd, 2017
In a quiet patch of thorny wineberry bushes on Staten Island, a white-tailed deer snored loudly, oblivious to the team of humans gathered around him.
For the two young does that looked on from a distance, it must have been a peculiar sight: One of the deer’s legs was roped up to a tree, his eyes were covered in blue fabric, and a tube in his snout delivered oxygen from a tank.
Nathan Kotschwar, a veterinarian, knelt on the dirt ground and quickly performed a vasectomy – slicing, stitching and stapling the deer’s hindquarters in less than 15 minutes.
The operation in Butler Manor Woods on a recent Tuesday was part of an effort by New York City’s Department of Parks and Recreation to reduce Staten Island’s growing deer population by sterilizing every male deer in the borough.
After the surgery, the deer’s ears were tagged with a number — 804 — and, about 25 minutes later, he woke up and groggily stumbled into the bushes.
By then, Mr. Kotschwar, who left the sleeping animal in the care of a colleague, was long gone.
“I’m going to go find the next one,” he had said, before disappearing into the woods.
In deer sterilization programs in cities across the country, including Cincinnati, Ann Arbor, Mich., and upstate in Hastings-on-Hudson, the does are usually targeted for surgical or chemical sterilization. The experiment in Staten Island is the first in the nation to try and cull the population solely though vasectomies, according to City Hall.
If successful, the experiment could serve as a model for other metropolitan areas overrun by deer.
“People said it was just not logistically possible to capture this many deer and sterilize them,” said Sarah Aucoin, chief of education and wildlife for the city’s parks department. “But we can tell you that it’s not logistically impossible. We are reaching the number of deer we were hoping for.”
The city oversaw 720 vasectomies last year, when the project launched, and they estimate that about 92 percent of the sexually active male deer on the island were sterilized. Last month, a six-person team began searching for the remaining adult bucks, as well as younger males, which they estimated to be about 250 in August.
For years, environmental officials and local leaders, including the Staten Island borough president, have said that the increased deer population was a nuisance and health hazard. Deer can put drivers in dangerous situations during the fall mating season, when the frisky animals cross roads in search of a mate. Last year, the Health Department confirmed 93 new cases of Lyme disease in Staten Island, a record high, and residents have complained about chewed-up flower beds and gardens. The parks department has fenced off parks and planted deer-resistant vegetation to keep the city’s greenery out of the mouths of hungry deer.
The parks department first began receiving regular reports of deer in the borough in 2000. With no natural predators, and hunting outlawed in the city, the population grew rapidly. The department estimates there are now about 2,000 deer on Staten Island — in 2008, a study by the state counted 24.
In 2015, Mayor Bill de Blasio assembled an interagency task force to deal with the deer. Last year, the parks department hired White Buffalo, a nonprofit organization led by Anthony DeNicola that works to conserve native species and ecosystems, to perform the vasectomies as part of a research project. The nonlethal experiment to reduce the deer population will cost the city $3.3 million over three years.
Because bucks can travel great distances to breed, sterilizing them requires covering a lot of ground. So cities with deer sterilization programs have mostly focused on sterilizing the female deer, which are more stationary. But on Staten Island, Dr. DeNicola saw an opportunity to do something different.
Namely, because it is an island, finding all of the males is possible, Dr. DeNicola, said.
The borough’s suburban geography also helps. Dr. DeNicola and his team cannot chase deer through backyards or dart them in populated areas. Instead, he waits for them to arrive at bait sites in wooded areas throughout the island.
“A family of females is social,” he said, meaning they travel in a group. “So after I shoot one, the others will watch her tip over. They learn pretty fast that this bait ain’t so good.”
Over time, he said, the females will learn to avoid the traps. But the bucks, which usually travel solo, almost always take the bait.
Also, he said, a vasectomy is less invasive and easier to execute than female sterilization.
That is not to say, though, that the parks department’s experiment in vasectomies is without problems.
“With any deer fertility control study, once you’ve started it, then there has to be constant maintenance for the foreseeable future,” said Paul Curtis, a professor at Cornell University and an expert on community-based deer management.
Even if 99 percent of the males are sterilized, he added, “you’re still going to see some immigration on the island.”
“So the question is,” he said, “can you get those new males when they first arrive and catch them efficiently and get them sterilized before they impregnate too many does?”
Dr. Curtis said the program on Staten Island also might not solve one of the borough’s immediate problems with the deer: car accidents.
“Typically deer vehicle accidents peak in November during the peak of the rut,” he said, using a term for the mating season. “Once the rut’s done, the number of accidents falls off pretty quickly in a normal herd.”
But if the females continue the mating season into late winter, he said, “there’s definitely the potential for an increased number of deer-vehicle collisions, particularly in January and February when the does continue to cycle.”
Dr. DeNicola disagrees. He believes the males determine the mating season. Come winter, when their testosterone levels drop, they will stop chasing the females around the island as they normally would, he said. “I just have to prove that.”
But even Dr. DeNicola will admit that the Staten Island experiment has its challenges.
Like traffic, for example. Getting one of the two veterinarians on staff to an unconscious deer in the car-dependent borough before the drugs wear off can be tough, he said.
And in the big city, the veterinarians must be flexible.
“After you dart a deer, they can run three or four hundred yards before it’s going to be down,” Dr. DeNicola said. His team operates on them where they fall: in industrial parks, cemeteries, or near the side of the road.
In the past, Dr. DeNicola and his team would sometimes carry the deer to a car and then drive them to a trailer for the surgery, before releasing them where they were knocked out. So far this year, his team has performed all the operations in the field, which he said is easier on his team, both logistically and physically.
If the program is successful and all the male deer on the island are sterilized, the population is expected to drop by 10 to 30 percent every year, Ms. Aucoin said. Once most of the male deer are sterilized, a program would need to be established to vasectomize any deer that may swim over from New Jersey, where the borough’s deer are thought to have originated.
The goal is not eradicating the deer from the island, she said: “We are looking to move the population to a sustainable level.”
“There’s an ecological carrying capacity, but there’s also a social carrying capacity,” Ms. Aucoin added. “How much do people want to see deer? How much of these impacts are they willing to live with?”