Dolphin, apparently healthy, swimming in New York's East River

NEW YORK (Reuters) - A dolphin swam up New York City's East River on Wednesday where it appeared to be doing fine despite straying from its more usual ocean habitat, officials said.

Until biologists get a closer look, it is hard to say whether it is a common dolphin, an Atlantic bottlenose dolphin, a white-sided dolphin or a white-beaked dolphin, said Kimberly Durham, the rescue program director at the Riverhead Foundation for Marine Research and Preservation.

"I've seen some video of it swimming, and it seems to be swimming fairly strong," Durham said. It appeared to be swimming around a fairly large area of the river, which was an encouraging sign, she said.

"I do get nervous when I see a lone animal," she added, explaining that dolphins are social animals that typically do not separate themselves from their pods.

A biologist from Riverhead was planning to take a boat out on the river along with officials from the state's Department of Environmental Conservation to photograph the dolphin, identify it and to assess its health, Durham said.

The dolphin was first spotted on Wednesday morning.

Police said they were no longer on the scene after notifying Riverhead, which oversees the monitoring of marine animals that enter city waters.

In January, a sickly male common dolphin died after becoming stranded in Brooklyn's polluted Gowanus Canal.

(Editing by Barbara Goldberg and Kenneth Barry)