CITY HALL -- There's a Bambi boom on Staten Island.

Roaming the borough are between 1,918 and 2,188 deer, according to a new estimate from the city contractor giving vasectomies to borough bucks.

That's about four times the city's last count and a 9,000 percent increase in the herd since 2008.

"This is the basic question we haven't really been able to answer," said Sarah Aucoin, Chief of Wildlife and Education at the Parks Department. "Many people assumed that there were fewer or feared that there were many more."

A Parks Department contractor performed vasectomies on 642 adult bucks and 78 younger, non-breeding male deer without antlers during the first season of the city's three year plan to cut down Staten Island's herd.

Anthony DeNicola and his team at the wildlife conservation nonprofit White Buffalo are also tracking deer on Staten Island with ear tags, radio collars and trail cameras.

DeNicola came up with the new estimate using data from the vasectomy program and typical suburban deer herd population dynamics. Past aerial surveys gave the city more information about the herd's distribution instead.

'IT'S OUTRAGEOUS'

Bernd Blossey, an ecologist at Cornell University who consulted City Hall on deer management strategies in fall of 2015, chuckled after hearing the new herd estimate for Staten Island.

"It's outrageous," Blossey said. "It's not unheard of, but it's interesting that the deer pack themselves in such a small area."

Staten Island is nearly 60 square miles. About a quarter is federal, state and city parkland.

If there are 2,000 deer in the herd, that's roughly 135 bucks and doe for every square mile of parkland on Staten Island. There were about 125 deer per square mile in the small village of Cayuga Heights in upstate New York near Cornell, according to a 2013 study.

Aucoin said that the deer aren't distributed evenly throughout the borough or even the parkland. But she said the herd's size proved the city was right to go forward with a plan without knowing the precise number of deer.

"Had we not done that, we would have been in more trouble than we are today...It was the right risk to take," Aucoin said. "We're able to better plan next steps and actions for year two and year three."

VASECTOMIES TO CUT THE HERD

The vasectomy effort is expected to eventually reduce the herd 10 to 30 percent on Staten Island.

If that happens and the latest estimate is correct, the herd would only be cut down to a minimum of around 1,340 deer.

"No deer on Staten Island is not a feasible goal, but we do want it to be at a manageable level," Aucoin said.

Some wildlife experts like Blossey thought the plan won't work because the city is ignoring basic deer biology and conventional herd management practices.

"You will not see a difference in the woods," said Blossey, who has been skeptical of the plan since last year. "In terms of making an ecological difference, it just becomes increasingly more difficult as the herd number increases."

White Buffalo estimates 92 percent of all mature bucks with antlers now have vasectomies. That means there's roughly 698 bucks on the Island in all, and most are sterilized.

But even 8 percent of breeding males -- around 56 bucks -- can impregnate dozens of doe. And it's unclear how many younger males that haven't been sterilized yet will grow up and breed in next fall's rut.

"An individual buck that is not sterilized can breed 20 or 40 doe over the winter," Blossey said. "Does this work? No, nobody would expect it would work."

White Buffalo will start performing vasectomies again in August, so many of the leftover males may be sterilized before they can breed.

DeNicola has also previously said that the biggest deer still believe they're fertile and "buck-block" others from breeding with doe.

"People will think like humans," DeNicola said last year. "But deer can't process what happened under the anesthesia to go, well, jeez, I'm not going to bother breeding anymore."

PAST SURVEYS

Only 527 deer were found on Staten Island during the city's latest aerial survey of the herd -- 236 less than a count three years ago and well below what the city expected.

The city only looked for deer on Island parkland in 2014, while the most recent survey in February 2016 was of the whole borough. Officials said fewer deer could have been found last year because the survey was done during warmer, less cloudy weather than in 2014.

A state Department of Environmental Conservation study from 2008 estimated the borough was home to roughly 24 deer. Wildlife experts speculated that the herd grew when deer swam across from New Jersey because of dwindling food sources and habitat loss.

The city believes the herd is now growing mostly through reproduction, not migration onto the Island. Sterilizing males instead of females is meant to be more humane, faster and cheaper.

$3.3 MILLION EFFORT

The city spent $2,778 for every deer vasectomy performed during the first year of the management program, according to Parks Department numbers. The contract with White Buffalo is for up to $3.3 million over a three-year research study.

An unrestrained and expanding deer herd can harm parks and private property, spread tick-borne illness and wander into roads more often, increasing the risk for deadly vehicle collisions.

Mayor Bill de Blasio said last week that a decrease in cars hitting deer may be attributed to the vasectomy program.

He said there had been a 89 percent drop in deer vehicle collisions this year through April 9, but the mayor's office said he was given wrong information. There was actually a 31 percent decrease, from 16 to 11 collisions during that time period.

"Maybe the deer are not happy about our particular strategic approach," de Blasio said with a laugh during an April 10 press conference in Tottenville.

Hearing this joke, Borough President James Oddo crossed his legs and said, "Let me just adjust myself as we talk about that topic."

'LET NATURE TAKE ITS COURSE'

DeNicola estimates that roughly 11 percent of the Island's deer herd died this past season.

Even after the three-year study ends, Aucoin said the city will have to continue to manage the herd.

"We're going to need to continue to monitor and perhaps do some -- I hesitate to say what -- do some management moving forward," she said.

Blossey is unconvinced that the city's vasectomy plan will actually reduce the population enough to control the herd's negative impact.

"People say, 'Let nature take its course,'" Blossey said. "But a whole bunch of deer are not much help...if that's what you're happy with, then let nature take its course."

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