Reindeer are the only members of the deer family in which both males and females grow antlers.
A solft skin called velvet covers these bone appendages as they develop. This soft skin covers a network of blood vessels that nourish the soft bone. After the antlers harden in late summer or early fall, the deer rub the velvet off. The main purpose of antlers is to display social rank. In the period of time after the males have shed their antlers and before the females have, the females become the dominant animals.