Deer are recognized by the striking bony structures that emerge from their heads. Understanding these unique growths reveals insights into deer biology and behavior.
Antlers vs. Horns: The Key Difference
Deer possess antlers, which are distinct from horns found on other animals. Antlers are extensions of the skull, composed entirely of bone, and are typically branched structures. They are generally found only on male deer, with the notable exception of reindeer (also known as caribou), where both males and females grow antlers. Unlike horns, antlers are shed and regrown each year.
In contrast, horns are permanent structures that are not shed annually. Horns consist of a bony core covered by a sheath made of keratin, the same material found in human hair and nails. Animals such as cattle, sheep, and goats possess horns, which are often unbranched. The pronghorn antelope is an exception, as it sheds its horn sheath annually, but its underlying bony core remains.
The Antler Cycle: Growth and Shedding
The growth of antlers is an annual process influenced by hormonal changes and daylight length. Antlers begin as soft, vascular tissue covered by a fuzzy skin known as “velvet.” This velvet is rich in blood vessels and nerves, supplying the necessary nutrients and oxygen for rapid bone growth.
As summer progresses, the antlers reach their full size, and the blood supply to the velvet diminishes. The velvet dries and becomes itchy, prompting the deer to rub it off against trees and vegetation. This process reveals the hardened, bony antlers underneath, which are then ready for the breeding season. After the breeding season, testosterone levels decline, weakening the connection between the antler and the skull. This causes the antlers to detach and fall off, and new growth begins shortly after.
Purpose of Antlers
Antlers serve several functions, primarily related to reproduction and social hierarchy. During the breeding season, known as the rut, male deer use their antlers in combat to establish dominance over rivals. These clashes determine access to females for mating, with larger antlers often indicating a male’s strength and overall health.
Antlers also play a role in display, serving as visual signals to attract mates and intimidate competing males. The size and complexity of a male’s antlers can signify his genetic quality and physical condition to potential female partners. While less common, antlers can also be used for defense against predators, though running away is typically a deer’s primary escape mechanism.