Antler Shedding
In the past, it was believed that deer withdrew to secluded places to shed
their antlers in order to avoid the loss of virility in 'public.' However,
it is likely that deer are unaware of when they will lose their antlers.
Antlers are shed when a thin layer of tissue destruction, called the
abscission layer, forms between the antler and the pedicle. This layer
forms as a result of the decrease in testosterone. As the connective
tissue is dissolved, the antler loosens and is either broken free, or
falls off on its own. This degeneration of the bone-to-bone bond between
the antler and the pedicle is the fastest deterioration of living tissue
known in the animal kingdom.
In whitetails, a restricted diet has been found to cause bucks to shed
their antlers early. It has been suspected that the lack of adequate
nutrition somehow effects testosterone output. Nutritionally-stressed
bucks may also grow their antlers and shed their velvet later. Older-aged
bucks are thought to shed their antlers earlier than younger bucks. It has
also been reported that higher-ranked (more dominant) bucks cast their
antlers sooner than lower-ranked (subordinant) bucks. Older-aged, more
dominant bucks probably shed their antlers sooner because of the high
energy costs incurred in maintaining a higher dominance rank.
The farther deer are from the equator, the more defined their antler
cycle. In other words, northern deer have a shorter "window" of when
antler shedding can occur, compared to deer herds in southern states. In
addition, the specific date when a buck will shed his antlers may be
determined more by his individual antler cycle than any other factor. This
cycle is independent of other bucks and is believed to be centered on each
animal's birth date.
Penned deer studies have allowed scientists to measure the exact dates of
antler shedding for individual deer year after year. One study in
Mississippi found that individual bucks usually shed their antlers at the
same time each year and almost always during the same week. Yearling bucks
with only spike antlers shed sooner than yearling bucks with forked
antlers, likely because they were more nutritionally stressed than
fork-antlered bucks. This study also indicated there was no relationship
between antler mass and date of antler shedding, although other studies
have shown that bucks shed their antlers earlier as they grow older.
Additional penned studies have also revealed that bucks usually shed both
antlers within three days of each other.
Although there is no clear evidence that weather directly affects antler
shedding, it is likely that severe winters may also cause bucks to shed
their antlers earlier than normal because of the nutritional stress this
causes.
Why Do Bucks Shed Antlers?
We have examined the environmental and physiological changes that occur to
cause bucks to shed their antlers every year, but we still haven't
addressed the question of why bucks shed antlers. Why do bucks spend so
much energy in growing antlers, only to shed these antlers a few months
later, forcing them to reinvest an enormous amount of energy to regrow the
antlers again the following year? Why don¹t deer antlers stay attached and
continue to grow throughout life like the horns of sheep, goats, and
cattle?
Scientists have pondered these same questions for many years and they
still do not know the answers. However, several theories have been
developed to explain why antlers are shed every year. One of the most
common theories is that bucks shed their antlers annually so that they
have the potential to replace any damage to antlers that may have occurred
in the form of broken tines, or a broken main beam. This theory seems
valid because antlers are extremely important in display for acquiring
females and because they are used during dominance fights with other
bucks. If a buck breaks a main beam and is not able to replace that
antler, it may not be able to acquire future breeding privileges.
A second related theory suggests that bucks shed antlers annually so that
they can regrow larger antlers the following year, in order to keep pace
with their increasing body size. This theory is based on the fact that
antlers quickly mature into nongrowing structures before the buck is able
to attain full body size.
A third theory states that antlers are shed simply because of an accident
of evolutionary chance. In other words, there is no real reason why
antlers are shed. Antlers are different from horns, not because they need
to be, but because of different evolutionary origin. A fourth theory
suggests that antlers are shed in order to stop the die-back process, that
occurs at the junction of the pedicle and antler, from traveling down into
the skull.
Another theory suggests that antler shedding developed in the primitive
antlers of ancestral deer from temperate zones. Antlers of deer in these
colder climates would have been vulnerable to freezing in winter if they
were not shed. The only way to prevent freezing would have been to stop
the blood supply to antlers before the onset of winter.
It is thought that ancestral males shed their antlers so that they were
able to mimic the healthier, nonantlered females. In theory, this reduced
their vulnerability to predation, because predators may have actively
searched for antlered males due to their weakened condition.
One final theory simply suggests that antlers are shed each year as an
energy-conserving measure, so that males don¹t have the added weight from
the antlers to carry outside of the breeding season. Antlers are
cumbersome and energy-expensive structures that are not needed after the
breeding season. However, for this to be true, it must also be true that
regrowing the antlers each year is less energy-expensive than maintaining
the antlers through winter. (By Dr. Mickey Hellickson )
I've lost both my cell phone and my camera before while hawking, and found both- my camera was in the bottom of a creek- good thing it was in a plastic bag! Phone evaded me during school once- i flushed it down the toilet i think by accident... Don't ask... I found a digital camera 12,800 feet up a mountain in Colorado- Couldn't find the owner though! I've been looking for arrowheads and feathers my whole life, and have developed a keen eye on the forest floor. Bones too- That first buried one only the base was sticking out, and I thought it was a bone until I pulled it out of the ground!