
Ted S. Warren / AP
A group of bison grazes, Monday, Feb. 14, 2011, just inside Yellowstone National Park near Gardiner, Mont. U.S. District Judge Charles Lovell in Helena, Montana, issued a ruling Monday, Feb. 14, 2011 in which he denied a request from wildlife advocates to stop the slaughter of potentially hundreds of wild bison from Yellowstone National Park that had attempted to migrate into Montana.

Ted S. Warren / AP
A government horseback rider hazes bison to move them from one location to another, Monday, Feb. 14, 2011, just inside Yellowstone National Park near Gardiner, Mont.

Ted S. Warren / AP
Bison are shown inside a corral facility along the northern border of Yellowstone National Park, Monday, Feb. 14, 2011, near Gardiner, Mont. Hundreds of bison are being held at the facility after they left the snowed-in park to find food at lower elevations.
For more about this issue, see a documentary film on the topic, a summary from the US Dept. of Agriculture, an activist group trying to stop the killing, and a comment from the director of Montana Fish, Wildlife and Parks.