6 Canadian Wolves Hesitant to Leave Pens at Yellowstone

Wildlife biologists opened the gate on a pen holding six Canadian gray wolves in Yellowstone National Park on Tuesday, but the predators were slow to accept their freedom.

The biologists left food inside and outside the pen after opening the gate, and the wolves treated the activity as a regular feeding, Yellowstone spokeswoman Sue Consolo-Murphy said. The animals gathered at the opposite end of the pen from the humans.

The biologists expected the wolves, each wearing a radio transmitter, to discover the open gate when they were left alone, she said. Automatic cameras have been placed to photograph their departure.