Yes, caribou do lose their antlers. Male caribou, also known as bulls, shed their antlers every year in preparation for the next mating season. The shedding process, called "antler cast" or "antler drop," usually occurs from late spring to midsummer. It's a natural part of the caribou's life cycle and helps the animals conserve energy for the coming winter. Female caribou, or cows, may also shed their antlers, but this is less common and not as dramatic as the shedding seen in bulls.