NEW YORK — If anyone knows why the bunnies have disappeared from Central Park, wildlife officials are all ears.

Though abandoned pet rabbits perennially turn up after each Easter in what's affectionately called New York's backyard, a wild cottontail hasn't been spotted in the park for about four years.

"I've been here for 17 years, and there were not many when I got here," Regina Alvarez, director of horticulture for the Central Park Conservancy, a nonprofit that manages the huge Manhattan park for the city, said in an e-mail. "But I would see them once in a while."

Only time will tell if they are gone for good, said Sarah Aucoin, director of Urban Park Rangers for the New York City Department of Parks & Recreation.

Cottontails seek habitats with lots of food sources and thick brush for protection, so it's possible there are still some hiding out. Rabbits have lived on the land since before the park was established 161 years ago.

Because bunnies "mate like rabbits," if there are still a few, "we'll see an increase, definitely," Aucoin said.

Jeffrey Croft, of the watchdog group NYC Park Advocates, said at least two other New York City parks have seen rabbits disappear in recent years.

The Eastern cottontail used to be plentiful on Randall's Island, between the Harlem and East rivers, but Croft said the population there vanished as its parkland was rehabilitated and redeveloped, and some natural fields were replaced with artificial turf.

Rabbits have also disappeared from Calvert Vaux Park in Brooklyn near Coney Island, he said.

Bunnies are vulnerable to a number of hazards, including weather, predators and automobiles — all features of urban parks, said state wildlife biologist Alan Hicks.

A recent storm took out large trees throughout Central Park, and several city streets cut through it. Hawks and falcons are a common sight there, and a random coyote is not out of the question. One was spotted in the park in 2006.

But Aucoin said she didn't think an increase in predators was to blame, because they generally don't decimate their own food source, she said.

"That's not smart, evolutionarily speaking," she said. "That predator population would die off if they didn't have anything to eat."

So since no one has the answer, officials are doing what they can to encourage repopulation. The city has been working to remove invasive plants and planting others to make the park more livable for small animals, including rabbits, Aucoin said.