Search This Blog

Thursday, 11 February 2016

BushScience; How Antlers Grow




We have been writing quite a bit about antlers recently on the Bushcraft Education blog and have shown you a few antler abnormalities over the last few weeks, first in Martins post and again just a couple of days ago. So it's about time we explain exactly what antlers are, how they work and what they are for. 



The first thing to understand is that antlers are made of bone and they are different to the horns of a cow or antelope which are made of keratin. Also antlers drop off every year while horn grows year on year and does not fall off.





Pronghorn - Antelope Island
A North American prong-horn Antelope
By Tortoise (Own work) [CC BY-SA 3.0 (http://creativecommons.org/licenses/by-sa/3.0)], via Wikimedia Commons


Antelope tend to grow horns with very simple shapes, single points, with a twist or spiral, and in the case of prong-horn with a single 'barb' or 'prong' on the front. In contrast deer, grow antlers with very complex shapes.





Like the palmate antlers of these Fallow Deer (picture Courtesy of David Carr)
Or the branched, multi pointed antlers of this majestic red stag (picture Courtesy of David Carr)
 
This Pere-David or 'Milu' at Woburn park has very strange antlers with backward pointing beams almost as long as the main beam of the antler.


On to antler terminology;

Antlers of this shape are unique to fallow deer
Antlers this shape are common on red and sika deer

There is plenty more antler related terminology, particularly related to Fallow deer and the development of their antlers as the animal ages;

  • Pricket; Young Buck typically with single point antlers before any palmation (flat bit) develops.
  • Sorrel; Three year old buck
  • Sore; Four Year old Buck
  • After that they may be known as 'bare bucks', 'bucks', 'master bucks' or 'great bucks' but by this stage unless you have kept track of a particular animal from birth and know exactly how old it is these terms have lost their value as something which indicates the age of the animal and is normally just based on how big the bucks antlers are, and there we hit a snag;
The size of a deers antlers is not determined primarily by age, although in fallow they do tend to go through stages of development with the size and shape of the 'palm' of their antlers developing over a period of years. It is food quality which determines antler growth and size more than any other single factor and so you will often see the deer with the best feed, ie; those which live on parks and deer farms where they are fed, growing much larger antlers than their wild counterparts. Deer are also capable of harvesting calcium from their own skeletons to contribute to the growth of their antlers, which does mean that if they are not on a particularly good diet while the antlers are growing they draw so much calcium from their own bones that they are effectively in a state of osteoporosis by the time their antlers are grown, this can lead to high mortality among stags and bucks after the 'rut' or breeding season as they are so weakened by the combined exertion of the breeding season and the growing of antlers. Partly for this reason deer (and other animals) eat the antlers cast in spring, which may explain why cast antlers are quite hard to find.

The thing that controls the growth of antlers is the hormone testosterone, the release of which into the male deer's system is triggered by the shortening days as we draw into autumn and winter. Once their system has testosterone in it ready for the breeding season the antler growth is stopped, while growing though the antlers are encased in a velvety like membrane which contains the blood and nerve supply to the developing antler. Each year this growth starts from scratch as soon as the previous antler drops off, once the antler stops growing though the velvet dries up and starts to fall off, during this stage of development the bucks and stags are known as being 'in tatters' as their antlers often trail long strands of drying velvet, they will often rub their antlers on trees and on the ground to shed these clinging strands and this explains the dark brown colour of most antlers. if they were not coloured by this rubbing and 'fraying' they would be pure white.  

 
this fallow buck is 'in tatters' and you can see how white his antlers are before he has had a chance to colour them up by rubbing and thrashing in the undergrowth. (Photo courtesy of David Car)




In the UK the main use deer have for their antlers is fighting and it's only the bucks and stags which grow them, although Chinese Water Deer have no antlers at all and are one of only a few deer species globally which don't grow antlers. In countries with harsher climates though antlers become useful tools and reindeer, whether male or female, all have antlers so they can dig through the snow.


So there you have it; an introduction to antlers, where they come from and what they are for. There are some other deer in the UK with very different antlers to the ones discussed here though and we have shown muntjac antlers fairly recently here on the bushcraft education blog  but have not addressed roe deer or their antlers in any great detail in the past. So in a couple of weeks I will dedicate a post to roe deer, their ecology, antlers and I will also answer the question I posed a few days ago, to which no one has given me an answer yet, What is a perruque? remember there is a prize of a set of Chinese Water deer tusks to the first correct answer.

Geoff 


Bushcraft Education Videos