Antlers as a Natural Clock

By Michael Ward

The growth of deer antlers and sheep horns are examples of a natural clock. The average age of a buck or ram can be told by how large his rack is. The larger the rack, the older the animal is. This is a good generalization for age, but there is no way to give a definite age as neither antlers nor horns grow at an exact constant rate, nor does it accumulate a given number of points per year. There are some differences between sheep and deer, however.

deerThe size of an individual buck's rack increases relative to itself with each passing year. When the buck is born, it does not have any antlers at all. It does not begin to grow them for approximately a year after it is born, but once growth does begin, it is very unlikely for the antlers to grow smaller than the previous year. Points are not added per year: a yearling buck may have anywhere from 2 to 6 points on his first rack, and that number will increase as he grows older. For the first few years, the number of points will increase, but as the buck becomes older the number of points seems to level off and the overall size of the rack (width and bone thickness) increases.

As a clock, the growth spans the life of the buck (anywhere from 10 to 20 years for whitetail deer) and can show three seasons each year: growth (summer/fall) in which the rack is covered in velvet (sensitive tissue that helps build the antler bone structure), shedding velvet (late fall/winter) when the velvet is shed from the antlers, and shedding of the rack (spring) when the rack falls off and the deer's body is preparing to grow new antlers.

ramsBighorn sheep are a little different: their horns grow a small ridge each year at the base, each ridge slightly larger than the last. Unlike deer, the horns do not fall off each year; they are continuously growing. Over time, the end ridges may be worn or broken off, but the ram's age may be approximated by counting the number of ridges still showing. Bighorn sheep only show the passing years, however. There is no change in the horns for each season, unlike deer.

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