Yellowstone National Park, WY - Buffalo
An American bison, or buffalo, appears to pose majestically beside the Madison River in snowy Yellowstone National Park in the western U.S. state of Wyoming. Note this fellow's radio-equipped collar. Such collars help National Park Service rangers keep track of herds -- especially to ensure that they don't stray outside the vast park's boundaries, where they would be inviting targets for hunters. Photo by Carol Highsmith.