Deer and their headgear
CHARLESTON, W.Va. -- Every fall, when West Virginians burn with deer-hunting fever, talk around the water cooler shifts from business and politics to tree stands and antler size ... and antler size ... and more antler size.
After all, bagging a buck with high, wide and handsome antlers is the stuff of which deer hunters' dreams are made. But what are these strange things called antlers? What are they made of? And, outside of being the objects of hunters' fascination, what purpose do they serve?
"They have two functions," said Jim Crum, deer project leader for the state Division of Natural Resources. "One is protection. The other is competition for mates."
Bucks use their antlers to shield themselves from attackers, and even to attack adversaries if necessary. Despite their apparent delicacy, antlers are surprisingly strong.
Researchers at Penn State University's Deer Research Center carry plywood shields when they enter pens during the whitetail-mating season. On occasion, bucks have wielded their antlers with enough force to penetrate the shields.
Bucks use their antlers most aggressively during the mating season in battles for dominance over rival bucks. The confrontations usually end after two bucks lock antlers and, after some pushing and wrestling, one animal proves physically superior.
The fights occasionally end with one or both of the animals injured, and on rare occasions can result in death, especially when the antlers become fully locked and neither buck can disengage. In 2010, three bucks in Meigs County, Ohio, became entangled and fell into the waters of Leading Creek, where they all drowned.
Crum said biologists used to believe that the strongest bucks with the largest antlers, having won the battle for dominance, bred the most females and sired the most offspring.
"We've since found out that while the big boys are out there shoving each other around, a lot of younger deer are sneaking in and taking care of business," he added. "Those findings kind of amazed us, because we'd always thought the big guys did most of the breeding."
Though some people colloquially refer to them as "horns," a deer's antlers differ dramatically from the horns of cattle, antelope, sheep and goats. Horns are made of keratin -- the same substance as human fingernails -- and stay attached to the animal from maturity until death.
Deer antlers are made of bone. They grow from pedicles, bony bumps found on the heads of all deer, and they drop off after the mating season ends.
"Both males and females have pedicles, but in most deer species only the males grow antlers," Crum said. "The exceptions are caribou and reindeer. It's an old joke among biologists that Santa's reindeer must all be females, because only the females retain their antlers that late into the winter."
Female white-tailed deer have the potential to grow antlers, too, but rarely do.
"It's rare, but occasionally we run across an antlered doe. Antler growth in females is usually triggered by a hormone imbalance or some sort of trauma," Crum explained.
In West Virginia, most bucks lose their antlers in January or February. Crum said he's seen bucks lose their headgear as early as late December, and he's heard reports of bucks retaining their antlers into April.
"One interesting thing about antler loss is that individual bucks tend to lose their antlers at the same time every year," he added. "Nutrition and testosterone levels tend to affect that, though. If bucks are nutritionally stressed, or if their hormone levels are interrupted, they might lose their antlers earlier than they otherwise would."
Antler growth starts immediately after the antlers are shed but it usually does not become visually apparent until late April or early May. Growth continues until approximately mid-August. While the antlers are developing, a fuzzy skin called "velvet" surrounds them. Each antler grows from this blood vessel- and nerve-laden covering. The bone that forms the antlers is spongy at first, but later mineralizes into hard bone.
Growth usually ends in August, and when it does bucks rub their antlers against trees to remove the velvet and polish the underlying bone.
Crum said growing that much bone, that quickly, is a drain on bucks' physical resources.
"That's why nutrition is the single most important factor in a buck's antler growth," he said. "The better the food a buck has, especially in late winter and early spring, the better antlers it can grow."
The second most important factor, Crum added, is age.
"The biggest increase in antler development is after a buck's first year," he explained. "A 1 1/2-year-old buck will usually have a little 'basket' rack with four or six points. The next year, when the buck is 2 1/2, the rack will be much wider and taller."
The older the buck gets, the bigger antlers it tends to grow. At 5 1/2 to 6 1/2 years of age, bucks reach their peak of antler development. "After that, growth starts to flatten out or decline," Crum said.
While genetics play important roles in human growth and features, Crum said they play only a minor role in antler size or shape among wild deer.
"The captive-deer industry places a lot of stock in bucks' genetics, but the simple fact is that nutrition and age are the main determinants of how big a buck's antlers get in the wild," he added.
White-tailed bucks aren't the only animals that grow new antlers every year. Male mule deer, elk, moose, black-tailed deer, red deer, fallow deer, roe deer and caribou also do.
But until elk become fully and permanently re-established in West Virginia's mountains, white-tailed deer antlers are going to remain the Mountain State's main topic of water-cooler conversation every autumn.
Reach John McCoy at 304-348-1231, or e-mail firstname.lastname@example.org.