Inaugurating the second year of the controversial wolf reintroduction program, a team of Americans coordinated by the U.S. Fish and Wildlife Service journeyed to Canada in January to capture a second group of wolves for release in the northern Rockies.

In frigid cold and heavy snow, the team located and sedated 37 wild wolves near the town of Fort St. John. Dart guns and helicopters were used to catch the wolves, which were then held in pens before being shipped to the United States.

Weighing around 100 pounds each, most of the wolves are three to four years old and range in color from brown-black to grayish-white.

Twenty of them were released into the wild in central Idaho, and 17 were placed in temporary holding pens in Yellowstone National Park.