Deer have become such a nuisance on Staten Island, the city is taking unusual action to control their numbers. NY1's Amanda Farinacci filed the following report.

It was a 140-pound white tail deer, living in the wilds of Staten Island.

A city contractor shot it with a tranquilizer gun, and brought it to a van, where a veterinarian and a biologist tagged it it and gave it a vasectomy under a new program to control the borough's exploding deer population.

"This was probably one of the more challenging projects, but things have gone smoother than we could have planned," said Anthony DeNicola, Ph.D, whose Connecticut company, White Buffalo, has a $2 million city contract to hunt and sterilize deer on Staten Island.

The animals have turned up on lawns and highways, spreading Lyme disease and causing nearly 50 car crashes last year alone on Staten Island, forcing the city and state to come up with a plan to manage their numbers.

"We're limited on our options," DeNicola said. "So we picked the option that was going to resolve the conflicts most effectively and efficiently, and the most humanely."

Beginning at twilight each night, 6 to 12, White Buffalo employees fan out across the borough with tranquilizer guns.

City Hall would not let NY1 film these 'hunts,' or say where food and surveillance cameras have been placed to lure the deer.

But once shot, small deer are brought to one of five mobile medical vans, then returned to where they were sedated. Heavier deer are sterilized in the woods.

In the month since the program began, officials say, 225 males have been given vasectomies. More than 1,000 deer are believed to be roaming the borough.

"The males are very healthy. Almost all the deer we've handled have been in very good shape," DeNicola said.

Part of DeNicola's job is to also place tracking devices on 50 females. The devices will allow his team to find out more about how deer are surviving on Staten Island, and whether the sterilization plan is working.

"We can look at the reproductive rates, which hopefully will impact the relative survival of the deer. And then you can do some simple math to determine if that population is changing," he said.

Officials won't say how many deer they want sterilized to prevent them from reproducing, only that this will continue until the spring.