Deer, found across many landscapes, possess a remarkable annual characteristic: their antlers. Most male deer species, along with female reindeer, shed their antlers each year. These unique bony structures are grown anew annually, serving various purposes before detachment.
The Annual Antler Cycle
The annual cycle of antler growth begins shortly after shedding, typically in late winter or early spring. Antlers emerge from specialized bony protrusions on the deer’s skull called pedicles. Initially, these growing antlers are covered in a soft, vascularized skin known as velvet, which supplies blood and nutrients for their rapid development.
Antler growth is among the fastest bone growth observed in the animal kingdom, with some species growing up to an inch per day. By late summer or early autumn, the antlers have reached their full size and begin to harden, at which point the velvet dries and is shed. Deer rub their antlers against trees and brush to remove the remaining velvet, preparing their hardened antlers for the upcoming breeding season.
The Biology Behind Antler Shedding
The shedding of antlers is controlled by hormonal fluctuations, particularly a decrease in testosterone levels. After the breeding season, or rut, typically in late fall to early winter, a buck’s testosterone levels naturally decline. This drop in hormones triggers the formation of an “abscission layer” at the base of the antler, where it connects to the pedicle.
This abscission layer is a zone where bone tissue is reabsorbed, weakening the connection between the antler and the skull. Once the connection is sufficiently weakened, the antlers detach, often falling off within a short period, sometimes even both at once or within days of each other.
Antlers vs. Horns: A Key Distinction
Antlers and horns are fundamentally different biological structures. Antlers are composed entirely of bone and are shed and regrown annually. They are found exclusively on members of the Cervidae family, which includes deer, elk, and moose, with the notable exception of female reindeer also growing antlers.
In contrast, horns are permanent structures that are never shed. They consist of a bony core covered by a sheath of keratin, the same material as human fingernails. Horns are typically found on animals in the Bovidae family, such as cattle, sheep, and goats, and can be present on both males and females. Unlike branched antlers, horns are generally unbranched and continue to grow throughout an animal’s life.
The Fate of Shed Antlers
Once antlers are shed, they become an integral part of the ecosystem. These discarded bony structures are a valuable source of calcium, phosphorus, and other essential minerals. Various animals, especially rodents like squirrels and mice, will gnaw on shed antlers to obtain these nutrients and to help keep their teeth worn down.
If not consumed by wildlife, shed antlers will eventually decompose, returning their minerals to the soil. The discovery of shed antlers by humans, a practice known as “shed hunting,” has become a popular outdoor activity. This allows people to connect with nature and collect these natural objects before they are reabsorbed into the environment.