Environmental groups are putting the Department of Interior on notice that they will sue if it doesn't return the West Virginia northern flying squirrel to endangered species status.

The U.S. Fish and Wildlife Service removed the animal. The agency said the squirrel had sufficiently recovered to be removed from protected status.

However, the Friends of Blackwater Canyon, Wilderness Society and others say the decision was not backed by science.

Friends of Blackwater's Judy Rodd said the squirrel is a relic of the Ice Age and is a subspecies of the northern flying squirrel found in Canada. It is only found in West Virginia and in Highland County in Virginia.

Wednesday's notice gives the federal government 60 days to seek a resolution before a lawsuit is filed.