The Smokies are home to over two dozen species of rodents, including the endangered northern flying squirrel, and 10 species of bats, including the endangered Indiana bat. The National Park Service has successfully reintroduced river otters and elk into the Great Smokies. An attempt to reintroduce the red wolf in the early 1990s ultimately failed. These wolves were removed from the park and relocated to the Alligator River National Wildlife Refuge in North Carolina.