STEPHEN J. KRASEMANN / SCIENCE PHOTO LIBRARY STEPHEN J. KRASEMANN / SCIENCE PHOTO LIBRARY
Barren Ground Bull Caribou (Rangifer tarandus) sparring with antlers, rut behavior to establish dominance. Members of the Porcupine Caribou Herd, which migrates between the Arctic National Wildlife Refuge (ANWR) and Yukon, Canada.
Model release not required. Property release not required.