Red-Necked Grebes in Central Park View Full Caption

NEW YORK CITY — The bitter winter that kept many New Yorkers shivering well into March had a silver lining for birdwatchers — driving rare ducks typically spotted only in climes further north down to the city.

Red-necked grebes, which normally stay in the northwest and Canada, have set up shop in Central Park and were spotted as recently as March 30, birders said. White-winged scoters, more common upstate but rarely spotted in the city, have been seen in Inwood Hill Park, sparking enthusiastic posts by birders on blogs, YouTube and the popular mapping website eBird.

Both species seemed to have moved south because the colder-than-usual winter temperatures froze their natural habitat — making it difficult for them to feed, said Andrew Farnsworth, a researcher at Cornell's Lab of Ornithology.

"When the freeze happens, they disperse to wherever they can find something that appears to have open water," said Farnsworth, who studies bird travel patterns. "There was a huge movement of water fowl off those lakes.

"The red-necked grebe were moving tremendously this year [traveling] as far south as they needed to go," Farnsworth said of the distinctively plumaged birds.

This winter was abnormally cold across the northern U.S. as arctic air froze 91 percent of the Great Lakes by the beginning of March along with many smaller bodies of water, according to the National Oceanic and Atmospheric Administration.

Typically, even in a cold winter, the Great Lakes retain some open water, allowing birds to continue to feed through the season, according to bird and weather officials.

The freeze has pushed other animals south as well, like young harp seals that have been spotted on several local waterfronts while they lounge in the sun and shed their baby coats to grew their more mature fur.

Along with the grebes and scoters, ground-feeders like horned larks and snow buntings have also been spotted in higher-than-usual numbers around the city because heavy snows made it hard to reach seeds on the ground, said Tod Winston of the New York Audubon Society.

And on March 6, a seal scooted itself up Rockaway Beach and sunbathed there for an afternoon to the delight of passerby.

"We're still seeing species that are regionally unusual appearing in New York City," Farnsworth added.

These winter birds will likely stick around for a little while, Farnsworth said.

But once the warmer weather hits towards the end of April and the beginning of May, experts expect the birds to head back north.