In my last Nature Smart column we looked at deer antlers. More specifically we examined the difference between horns and antlers. (Yes there is a difference.) We also learned that antlers are composed of calcium, just like bones. In fact antlers are the fastest growing bones in the mammalian world. Where all of this calcium came from to build the antlers was even more interesting. Bucks pull the extra calcium from their ribs and sternum, making the bones prone to rib fractures.
In fact the mobilization of minerals from the skeleton to a White-tails antler’s is so remarkable it may someday give us an insight into the mysteries of osteosarcoma (bone cancer) and also osteoporosis (a serious bone disease of older women). There is much to learn from Mother Nature.
I am always amazed at the different color of antlers. They can range from Ivory to dark mahogany. The coloration comes from staining due to rubbing the antlers on tree bark or from the stain of blood hemoglobin when the antler is still in velvet. I have also seen antlers with different colored moss and lichen growing on the antlers, particularly at the bases, which makes them look different colors.
By the end of the mating season a bucks antlers can be nearly white. Rain and sun do much to bleach the antlers. And by the end of January and occasionally February, bucks will shed or discard their antlers. Casting or shedding of the antlers occurs with little to no pain and very little blood. In fact the attachment spot heals quickly, usually within a couple days and new antlers start to grow within weeks starting the process all over again.
Discarded antlers just don’t lie around the forest floor forever. No they are chewed upon, presumably to gain the calcium, by a host of small mammals. In fact a friend of mine once drilled a hole through a deer antler and threaded a heavy gauge wire through it. He then secured the antler to the ground with the wire and took note how long it took for the antler to be eaten. In a short 8 weeks there wasn’t much left of the antler.
As incredible as antlers are, what is even more incredible is why a deer has antlers in the first place. Think about it. Of what use are a buck’s antlers? If you examine a buck’s entire year you will find that antlers are more of a hindrance than help. Think of it, from the day the antlers start to grow a deer must take great care to not injury the delicate growing antlers. During spring and summer bucks act and move around like does rather than the usual wild-eye buck. During this time, any disagreements between bucks is handled doe-like, with much rearing on hind legs and flailing with their forefeet because they need to protect their growing antlers.
During summer it is the females that are dominant, not the bucks. In fact there is good evidence that bucks live in summertime bachelor groups because the does have driven them into segregation. So why do bucks have antlers?
A common theory is that bucks grow antlers to defend against natural enemies and other bucks. But if that was true, why don’t female white-tails have antlers as well? The does are preyed upon even more than the bucks. Also, why don’t the bucks retain their antlers (more horn-like) throughout the winter when the predation is the worst? Besides isn’t a white-tails best defense its ability to quickly run away. Every deer I have come across has responded to me by running away and not standing and fighting.
A new and more intriguing theory as to why bucks have antlers is now coming out and there is some good evidence backing it up. We will take a look at this way of thinking about antlers and also look at a trip I took to Canada to photograph moose with a moose biologist who is studying the size of moose antlers and what they are used for. Until then …