Lucy Cooke explains why the females of this Christmas icon have antlers too
REINDEER
Reindeer are synonymous with Christmas. But are the antlered beasts that pull Santa’s sleigh male or female? Rudolph has antlers, so he must be a male right? Well, it’s not that simple. Reindeer are the only species of deer for which males and females both grow a set of seasonal armaments – a bit of detective work is required in order to work out the sleigh-puller’s true sex.
Antlers are considered a classic example of sexual selection – the evolutionary force that arises from the struggle for mates. Male reindeer use these elaborate bony outgrowths to fight one another over access to groups of females. During the annual rut they’ll lock horns in battle – shoving one another like Sumo wrestlers trying to eject an opponent from the ring. Females will shop around male territories and preferentially choose to mate with those sporting the most impressive head gear. Antlers are energetically expensive to grow, and an indication of a male’s size, strength and overall health. Mating with a winning male ensures the best genetic stock for their offspring, and so the male with the biggest antlers gets to sire the most.
The fact that female reindeer also sport antlers is something of a conundrum. Why would females bother to grow such a costly adornment when they need all their energy to raise offspring?
The answer is in the reindeer’s circumpolar environment. All six species are found in countries surrounding the Arctic and are suitably adapted for a life in the freezer. They have a hairy muzzle to reduce heat loss and very broad hooves to help them walk on snow. They are also the only deer that can digest lichen, which sustains them through the long winter months. But not without some
