Caribou, also known as reindeer (Rangifer tarandus) in North America, is a species of deer with circumpolar distribution, native to Arctic, sub-Arctic, tundra, boreal, and mountainous regions of northern Europe, Siberia, and North America. Black spruce (Picea mariana) and white spruce (Picea glauca) in pure or codominant stands with lichen-moss understories are heavily utilized as habitat in Alaska.
Caribou have the second largest antlers among all deer. Antlers harden in late summer and then shed their velvet once they quit growing. The velvet dries and falls away when its blood supply ends. Bucks often hasten the process by rubbing their antlers against trees or brush, possibly because the dying velvet causes an itching sensation. This bull spent this late August morning using the spruce to remove the velvet from his antlers leaving traces of blood, easily seen on the brow tine.