"If they'd delisted when the numbers were smaller, the states would have been seen as heroes and good managers," said Ed Bangs, wolf recovery coordinator at the U.S. Fish and Wildlife Service. "Now people will say they're murderers."

From the 41 animals released inside Yellowstone National Park from 1995 to 1997, the population grew to 650 wolves in 2002, and more than 1,500 today in Wyoming, Montana and Idaho, The New York Times reported Wednesday.

The population is growing about 24 percent a year, according to federal figures. Wyoming has pledged to maintain at least 15 breeding pairs in a five-county region around the park.

"I support no wolves on private land, and right now we have wolves running rampant," said Chip Clouse, a longtime Wyoming rancher.

"They brought the wolves in for people to see on the public lands, in the park, and what has happened is that they have grown so many packs that they're now impeding on people who are just trying to live and make a living on their own property."