All
About Antlers
One unique characteristic
of the deer family is their antlers. While horns remain permanently
affixed to the skull, antlers are shed every year. The exception
to this rule is the American pronghorn antelope; they shed their
horn sheaths once each year (the pronghorn’s bony horn cores
are not shed). Washington state species that grow antlers each year
include deer, elk, moose, and mountain caribou. Antlers form beneath
a covering of living skin. This skin, often called velvet, is complete
with hair, a very sensitive nerve network, and blood vessels. When
antler growth is complete the velvet dries, shreds, and peels off,
leaving the hard, mineralized antler ready for the breeding season.
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Figure
1. A deer’s first antlers are fully grown spikes or
small, forked antlers with two points.
(Drawing by Darrell Pruett.) |
Male fawns develop
buttons (small bumps on top of the head) at six to eight months of
age. These buttons are the rudimentary beginnings of the young buck’s
first antler set. Just before the fawn’s first birthday, these
velvet-covered buttons begin to elongate, growing from bony extensions
of the skull known as pedicels. By September these first antlers are
fully grown spikes, or small, forked antlers with two points (Fig.
1). Each
year, the antlers tend to grow in mass and diameter. Older bucks
tend to have more antler points than younger bucks, but the number
of points is not a reliable indicator of actual age. Antler size
and conformation also respond to nutrition, and thus serve to advertise
the physical condition of the buck. Rich feeding in captivity has
produced five-point antlers on yearlings, while a meager food supply
can limit even dominant bucks to forks. Bucks generally attain adult-size
antlers when they are four to five years of age, but the size and
weight of the antlers may continue to increase each year until age
ten.
Antlers serve
to establish dominance hierarchies among bucks. Big antlers, like
bright feathers on male songbirds, are an example of fitness evolved
through sexual selection. Because large antlers mean a buck has
either survived many years, has superior genetics, or uses high-quality
areas, bucks with large antlers make good sires for a doe’s
fawn. Does tend to select dominant bucks with large antlers for
their mates, and this selection enhances the success of bucks with
large antlers even more.
Bucks carry
their antlers through the fall, dropping them between late December
and early March. Hormonal changes cause a weakening of the bone
at the tip of the pedicel, where the antler-growing center is located,
and the pedicel/antler connection eventually becomes so weak that
the antler separates and falls from the pedicel.
Most antlers
that have been on the ground for more than a few weeks will show
considerable signs of gnawing by smaller animals, and after a year
most of the antler points will have been considerably shortened
by these mineral craving critters. Dropped antlers are chewed by
mice, rats, squirrels, hares, and porcupines, helping them to sharpen
their front teeth while supplying them with calcium, phosphorus,
and other minerals. (For additional information, see "Elk
Rubs" and "Collecting Antlers"
in Elk.)
Note:
It is legal to collect naturally shed antlers of deer, elk, and
moose.
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