Deer are taking over in the village of Hastings-on-Hudson.

Village officials and a team of experts started a research project to see how they could lower the deer population in the area.

Dr. Daniel Lemons, a village trustee, says the deer are anesthetized with a dart and injected with an immune contraception. The project also then takes blood samples of the deer.

Officials say this raises an immune response that interferes with sperm being able to fertilize an egg.

Dr. Lemons says he feels that this project is 90 to 95 percent effective.

With permissions from the state Department of Environmental Conservation, the experiment does seem to be working, but there is still not enough data to be sure. Researchers have devised a method to test if the population is in fact getting smaller. It's called the “host to hasta” program.

"Fifty households all around the village put a hasta plant in a pot and they check it every day, and then they report back in how long that plant has survived without being eaten," said Dr. Lemons. “We saw a doubling of the time that those plants would survive.”

Village officials say this is the best way to safely and cost-effectively lower the deer population.