Antlers are distinctive bony structures extending from the skulls of deer and represent a biological adaptation. Unique to members of the Cervidae family, these appendages vary significantly in size and complexity across different deer species. They serve various purposes.
Male Deer and Antlers
In most deer species, antlers are a characteristic feature primarily seen in males, often referred to as bucks. These elaborate structures serve multiple functions, particularly during the breeding season. Male deer use their antlers for display to attract mates, signaling their health and genetic quality.
Antlers also function as weapons in competition with other males, helping to establish dominance and secure breeding rights. Their growth is controlled by hormones, with increasing daylight hours triggering testosterone production, which initiates and regulates bone growth. Antlers can grow rapidly, sometimes as much as an inch or more per day during peak periods.
Female Deer with Antlers
While antlers are predominantly associated with male deer, female deer, or does, can also grow them. In most common species like white-tailed deer or mule deer, this occurrence is rare. Such antler growth in females is linked to hormonal imbalances, such as elevated testosterone levels, or sometimes to injuries. These antlers are often smaller and may remain covered in velvet or only partially harden.
The reindeer, known as caribou in North America, is a notable exception where both males and females regularly grow antlers. Female reindeer antlers are generally smaller than those of males. They retain their antlers through winter, often until they give birth in the spring, using them to compete for food by scraping snow and to defend their young.
The Antler Cycle
Antlers are unique among animal headgear because they are shed and regrown annually. This cycle begins with growth from permanent bony structures on the skull called pedicles. During their active growth phase, antlers are covered by a soft, vascularized skin known as velvet. This velvet supplies oxygen and nutrients to the rapidly growing bone beneath.
Once the antlers reach full size and harden, typically by late summer or early fall, blood flow to the velvet ceases. The velvet then dries and becomes itchy, prompting the deer to rub it off against trees and shrubs, revealing the polished, hard bone underneath. After the breeding season, usually in late winter or early spring, the antlers weaken at the base and fall off, and the cycle begins anew.
Antlers Versus Horns
Distinguishing antlers from horns is a common point of confusion, as they are different types of headgear found on various animals. Antlers are composed entirely of bone and are typically branched. A defining characteristic of antlers is their annual shedding and regrowth.
In contrast, horns are permanent structures that are not shed. They consist of a bony core extending from the skull, covered by a sheath made of keratin, the same material found in human fingernails. Unlike antlers, horns are generally unbranched and grow continuously throughout an animal’s life. Animals such as cattle, sheep, goats, and bison possess horns.