May Moose Antlers

These spring moose antlers on this older bull will grow to nearly 5' wide and 50 lbs by fall

Two mornings ago, I headed up into the Many Glacier valley after working all night just a few miles away. It was nice and quiet on the human front at 4 a.m. - too dark for the roving herds of ubiquitous photographers, too early for the glassy-eyed employees who live there. But the animals were active as always, and I counted seven moose feeding between the highway and developed area, five adults and two yearlings, including a pair who appeared to be looking in the windows of one residence.

Moose calves won't hit the ground until early June. But the male equivalent, antlers, started appearing several weeks ago. Energetically speaking, a pair of calves and a large pair of antlers are supposed to require about the same amount of caloric input. Cows give birth to 1 or 2 calves weighing 25-35 lbs. each, while big bulls grow a pair of annual antlers that span up to 60" wide with a combined weight of up to 50 lbs.

Moose are the largest member of the deer family, and in Montana we have the smallest sub-species, the Shiras' moose (Alces alces shirasi). Regulating hunters helped North American moose populations grow for most of the 20th century, but populations started plummeting again in the early 1990's. A combination of factors include at least two that are related to climate change. Moose evolved in cooler climates, and they do not have sweat glands for cooling in summer. Increasingly, heat stress is causing moose to seek shade and remain inactive for long periods. And warmer winters means less tick kill-off, and tick infestations are now growing and weakening otherwise healthy moose, which are then more susceptible to predation and disease.

Yearling moose in pre-dawn light

Instead of facing the new reality, Montana punted by initiating an 8-10 year study to identify the (known) causes of declines. The state agency seemed to feel this was necessary because they feared the bellicose minority of "hunters" who think that all wild animals belong exclusively to good ol' boys with more bullets than brain cells. They blame the moose decline on wolf reintroduction, of course, as if moose and wolves didn't evolve together over many thousands of years, both surviving quite well until the 1990's. Waiting 10 years allows the current managers to avoid the consequences. Unfortunately, moose don't have that option.

Young Bucks

Young white-tailed deer buck with antler deformities

At first, I didn't notice the unusual antlers on this young white-tailed deer (Odocoileus virginianus). His antlers were small, slightly deformed and still covered with velvet in mid-September, the time of year when most of our bucks are ready to rumble with hardened and polished antlers. His left side looked to be growing a late but otherwise normal spike. The right side was trying to grow a short, double main beam.

What might cause this odd antler growth? Age and genetics both play a roll in antler growth, but the primary factor is nutrition. Antler deformities, however, are almost always caused by injury.

"Buck rub" tree

White-tailed bucks grow their first set of antlers during their second summer. Antlers begin growing in March or April and normally finish by August or early September. First-year antlers are usually single spikes that represent about 10% of his adult antler potential. A buck reaches 50% of his antler potential at age three. And if he lives to maturity, at 5-8 years, he will fulfill his antler size potential only if his home range grows the right kinds of foods in the right seasons.

While growing, velvet-covered antlers are very delicate and easily damaged. Bucks will carefully turn and twist their heads to avoid scraping their soft antlers against branches. If roused to defense, he will use his sharpened hooves instead of his antlers. It's injuries to velvety antlers that cause the sort of irregularities that I eventually noticed on this young buck. Odd points, double main beam, slow growth. Most injuries won't affect next year's antlers, unless the injury occurs close to the antler base (the "pedicle") or on the skull.

Asymmetrical white-tailed deer antlers

Full-grown antlers harden in the fall, when bucks scrape off the velvet and polish their new antlers brown by rubbing them against small trees, called "scrapes" or "buck rubs." The bucks begin sparring and establish a dominance hierarchy for breeding. Dominant males don't defend a territory, but instead they defend the area around a doe and attempt to drive away all competitors. After the breeding season, the bucks will start shedding their antlers in February, later in more southerly states.

White-tailed deer are primarily browsers (small stems and twigs, forbs), and they eat grass only in the spring. Springtime is the nutritional peak each year, and stems and forbs are eaten in equal amounts. Selection for small stems and twigs slowly increases as forbs decline in nutritional value through the summer. One shrub species, Western Snowberry (Symphoricarpos occidentalis), accounted for almost one-third of the summer contents of deer rumens sampled in the Missouri River bottom lands of northcentral Montana.

In the fall, the end of antler growth allows for fat build up. Deer will seek out foods with high levels of carbohydrates, to be stored as fat reserves and used for fall breeding and winter survival. Their winter diet is almost entirely woody browse.

All of this plant material must be broken down in the deer's four-chambered stomach. In the first chamber, the rumen, there are large quantities of bacteria and protozoa for just this purpose. What's interesting is that these microflora in the rumen are plant-specific. That is, one species of protozoa only works to break down one species of plant.

Spotting a healthy buck with large antlers is a favorite fall pastime in our neck of the woods. Spying one with atypical antlers is even more intriguing. Still, there's a lot more going on with these deer than what is visible to our eyes.

Yearling elk with normal antlers (left) and damaged pedicle with drooping tine (center)

Buck Fever

Antlers have been ground up and used in medicinal potions for over 2,000 years in China. And yet here in Montana, the mere sight of a deer antler causes sweaty palpitations among many males of the human species.

Visions of big antlers cause recurring, hard to cure cases of "Buck Fever" every fall and every spring.

Antlers are the only mammalian organ that can be repeatedly regenerated, and this raises the heart rates of hunters and endocrinologists alike. Antler stem cell research is currently underway. Analyzing antler formation may help us understand why regeneration is limited in other animal (ie, human) tissues.

Antlers are not horns. Horns are permanent (not shed), unbranched head ornaments that are made out of a bony core that is permanently covered with a hard, keratinized sheath that is sort of like your fingernail. Think of bighorn sheep and bison horns as very large, very intimidating fingernails. Horns usually adorn both the male and female members of the species.

(The pronghorn antelope is a notable exception to two of the horn rules. Their horns are branched, and they shed the horn sheaths each winter.)

Antlers are different. They are basically a pair of bones that are regrown and shed once each year. And except for caribou, only males grow antlers. (Normally. Females can be chemically induced to grow antlers, and this occasionally happens in the wild.) By the time the young buck is six months old, stem cells differentiate on the lining of the frontal skull bones. These cells form a "pedicle," or knob, that all future antlers will emerge from.

Antler growth is regulated by hormonal secretions, which in turn are regulated by the length of daylight ("photoperiod"). Air temperature plays no role. Lengthening daylight hours in late spring turns on the mechanism for antler growth, and in winter the decreased daylight hours causes antlers to be shed, by resorption of calcium at the pedicle.

By manipulating the amount of light that captive deer are exposed to, stem cell research has shown that deer can grow and shed new antlers as fast as every three months or, conversely, as slowly as every other year. The three-month antlers were small and unhardened when shed, and two-year antlers didn't grow any larger than normal.

In the wild, antlers start growing in April or early May. Early antlers are high in water and mineral content, and covered in "velvet" skin. Antlers are the fastest growing organs in the animal world, capable of extending more than three-quarters of an inch per day. They will even pull calcium from the skeletal bones if necessary. Near the end of the growth cycle, spongy bone changes to compact bone on the antler's exterior, and the velvet dies. The animal rubs the velvet off on trees and brush, and this polishes the bone-white antlers into a shiny brown.

Sighting a shiny-brown, shed antler laying in the grass is how most people get infected with Buck Fever.

Due to this irresistable antler attraction, most of the larger Wildlife Management Areas (WMA) in Montana, and other Rocky Mountain states, now restrict human access between New Years' and May 15th. This keeps the ethical "horn hunters" from disturbing the wildlife during spring. But a WMA manager once planted 77 marked antlers in a closed area, and almost half of them went missing before opening day.

Opening day (actually high noon at many WMA's) can turn into a mad dash of people on foot, on horseback, and on four-wheelers. But if you prefer, a private, 4-day 3-night "Shed Antler Hunt" in central Montana is currently advertised for only $1,700 per person, gratuity not included.

You might have to feel awfully feverish before spending that many bucks to look for a few used bones. Just walking in the woods on a regular basis would probably keep us all healthier, wealthier -- and happier.

Behind the buck (above right): Photographed with 300mm f2.8 lens on a Nikon film body, somewhere in the woods of Glacier National Park. It's good for your health to wander around aimlessly in the woods every now and then. But if you find an antler (unattached to a buck) in a national park, leave it where you found it. The rodents will chew it up for calcium, and you can leave without getting to know the park Rangers (and maybe the local judge).