From the NYS DEC webpage.

The Eastern Cougar, or Mountain Lion, is listed as an endangered species in New York. This animal was historically present in the state but has been absent since the late 1800s, except for a few that are kept in captivity under a special permit. Officially, cougars are considered extirpated from the state. However, sightings of animals believed to be cougars are commonly reported to the regional wildlife office.
Black panthers are color variations of the jaguar from South America or the leopard from Asia, but sightings of such animals are also reported in New York occasionally. The fisher, a resident New York furbearer, is often mistaken for and reported as a black panther.
Evidence Needed
To date, no hard evidence has been produced that would prove the existence of cougars living in the wild in New York . . . no tracks, scat, dead cougars, photos, videos, or audio tapes. If you believe that you have seen a cougar, please check for tracks or other signs that have been left by the animal. If possible, photograph the animal. A sighting report form is available from DEC's Region 8 Wildlife Unit to record your sighting, or one can be printed off our website with Acrobat Reader (Cougar Sighting Form).
Wildlife staff will only investigate reports where some evidence exists, other than a visual sighting, or when a captive animal has been reported to have escaped.
Email Rumors
Staff has been responding to forwarded email's regarding unfounded rumors about cougars.
Examples of these email's are as follows:
[ul][*]a photo of a cougar stalking a mule deer (NYS has only white-tailed deer)[*]three photos of a cougar-one peering into a glass door, two with snowflakes falling around them[*]two photos of a man posing with a HUGE cougar (actually from the state of Washington) [/ul]
All are claiming to have originated in some town in New York State, but they don't. Please don't forward them.
A popular tale, but not true . . .
Rumors have been circulating for the past few years that the DEC has released cougars to control deer populations. Some of these rumors claim that Officer 'Jones' participated in the release, or that people have actually seen cougars with ear tags or neck collars, so they must have been released by the State. This is not true. The DEC has never released cougars, despite what you may hear to the contrary.