The announcement was made Tuesday, The Rocky Mountain News reported.

An environmental group, WildEarth Guardians, filed a complaint several months ago claiming that the federal agency was failing to carry out its duty to protect prairie dogs.

The animal, found east of the continental divide in Plains states from Texas and New Mexico to Canada, is often considered a pest by many people. Ranchers complain of livestock breaking bones after tripping in prairie dog holes and say that they spread disease.

Loss of habitat and other factors have greatly reduced prairie dog numbers, the newspaper said.

Fish and Wildlife officials said that Tuesday's finding, published in the Federal Register, is only preliminary.