Antlers are unique bony structures found primarily on male deer species, including white-tailed deer, elk, and moose. Unlike horns, which are permanent and grow continuously from the skull, antlers are deciduous. They undergo an annual cycle of growth, hardening, and eventual detachment from the animal’s head.
The Process of Antler Shedding
The process when antlers fall off is called “antler shedding” or “antler casting.” This involves the natural detachment of the bony structures from the pedicles, which are permanent extensions of the deer’s skull. Deer may rub their antlers against trees or other objects in the days leading up to shedding, which can help dislodge them. The shedding event can happen quickly. The shed antlers, often referred to as “sheds,” are a valuable source of minerals like calcium and phosphorus for rodents and other animals in the wild.
Biological Mechanisms of Shedding
The shedding of antlers is primarily controlled by fluctuations in hormone levels. A decrease in testosterone, triggered by shortening daylight hours, plays a significant role in initiating this process. This decline stimulates osteoclast-mediated bone reabsorption at the pedicle-antler junction. Osteoclasts are specialized cells that break down bone tissue, creating a weakened zone.
Concurrently, an “abscission layer” forms at this junction. This layer increases porosity and reduces bone density, further facilitating separation. The weakened connection allows even minor impacts or movements to cause the antler to detach. This physiological event ensures the antler detaches cleanly. Once shed, the exposed pedicle typically heals quickly, forming a protective scab until new antler growth commences.
The Annual Antler Cycle
Antler shedding is a regular phase within an annual cycle of growth and regeneration. Following shedding, which typically occurs from late December through early March, new antler growth begins almost immediately. During this initial growth phase, the developing antlers are covered in a soft, vascularized skin known as “velvet.” The velvet supplies blood, nutrients, and minerals to the rapidly growing bony tissue underneath.
Antlers grow throughout the spring and summer, with their size and complexity influenced by the deer’s age, nutrition, and genetics. By late summer or early autumn, the antlers have reached their full size and begin to mineralize and harden. At this point, the blood supply to the velvet diminishes, and the velvet dries out and begins to peel off. Deer will rub their antlers against trees or brush to remove the remaining velvet, a process known as “rubbing” or “stripping.”
Once the velvet is completely removed, the antlers are fully hardened and ready for the breeding season, which occurs in the autumn. After the breeding season, as daylight hours shorten and testosterone levels decline, the cycle culminates in the shedding of the hardened antlers, preparing the deer for the next year’s growth.