"A roundup of wild horses began Monday in northwestern Colorado over the objections of animal advocacy groups.
The U.S. Bureau of Land Management began herding the horses near Meeker into corrals using helicopters Monday afternoon.
Over the coming days, the agency hopes to gather about 140 horses that have moved outside public land designated for the animals.
Groups including the American Society for the Prevention of Cruelty to Animals and the Colorado-based Cloud Foundation sued in U.S. District Court in New York last week to try to stop the roundup.
BLM spokesman David Boyd said the animals slated for removal are outside a 190,000-acre area of public land designated for wild horses."