The U.S. Fish and Wildlife Service (FWS) is planning to remove the eastern cougar from the endangered species list after determining the subspecies has likely been extinct for 70 years.

The proposal comes after a formal review of the subspecies' status that concluded in 2011. Wildlife officials looked at more than 100 reports (going back to 1900) and found that recent "sightings" of the eastern cougar were actually of Florida panthers, wild western cougars or other cougars that escaped from captivity or were released.

The FWS also looked at available historical and scientific studies, and consulted experts in 21 U.S. states and some eastern Canadian provinces. [5 Mysterious Animal Die-Offs]

"We recognize that people have seen cougars in the wild in the eastern U.S.," Martin Miller, the service's northeast region chief of endangered species, said in a statement. "Those cougars are not of the eastern cougar subspecies."

Meanwhile, wild western cougars have been moving east over the past two decades, FWS officials said. Usually, these cougars end up in the Midwest, although there have been isolated cases of cougars traveling even further east than that, the officials added.

For example, in 2011, a male cougar was tracked from South Dakota through Minnesota, Wisconsin and New York before it was killed on a highway in Connecticut. Another cougar was killed in Kentucky in 2014, although its origin was not determined, FWS officials said.

The eastern cougar has been classified as "endangered" since 1973, but the last records of the animal date back to the 1930s in Maine and New Brunswick. Most of these cougars were killed in the 1800s as the result of European immigrants clearing forests. Those immigrants also killed the animals out of concern that the large predators would hunt livestock. In addition, populations of eastern cougars dwindled when white-tailed deer (which the cougars feasted on) nearly went extinct in North America.

The proposal to remove the species is posted on the Office of the Federal Register website. It will be available for review and comment until Aug. 17. Another cougar species, the Florida panther, remains on the endangered species list.

 

Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.