Elk exhibit a remarkable annual cycle involving the growth and subsequent shedding of their antlers. This process distinguishes them from animals with permanent horns. Each year, male elk, known as bulls, develop bony structures on their heads, only to shed them and regrow a new set.
How Antlers Grow
Elk antlers are true bone structures, not horns, and they grow directly from bony protrusions on the elk’s skull called pedicles. This growth process is among the fastest known in the animal kingdom, with elk antlers capable of growing up to an inch per day during their peak phase. During their development, the growing antlers are covered by a soft, fuzzy skin known as velvet.
The velvet is rich in blood vessels, providing the necessary nutrients and oxygen, including essential minerals like calcium and phosphorus, to support the rapid bone formation. As the antlers near full size, typically by late summer, hormonal changes cause the blood supply to the velvet to diminish. The velvet then dries and begins to peel away, a process often aided by the elk rubbing its antlers against trees and shrubs, revealing the hardened, calcified bone underneath.
The Biological Reasons for Shedding
The shedding of antlers is controlled by fluctuations in hormone levels, particularly testosterone. After the breeding season, a bull’s testosterone levels begin to decline. This decrease in testosterone triggers a process where specialized cells reabsorb bone tissue at the base of the antler, at the pedicle. This reabsorption weakens the connection between the antler and the skull, eventually leading to the antler detaching and falling off.
Shedding antlers provides several biological advantages for elk. Antlers are metabolically expensive to grow and maintain, requiring significant energy and mineral resources. By shedding them after the breeding season, elk conserve energy and nutrients that would otherwise be expended on carrying and sustaining these heavy structures through the leaner winter months. The annual shedding also allows for the regeneration of new, potentially larger and stronger antlers each year, which are important for displaying dominance and competing for mates in the subsequent breeding season.
Life After Antler Loss
Immediately following antler shedding, the pedicles heal quickly. New antler growth typically commences almost immediately, often within a few weeks after the old antlers have fallen off, usually in late winter or early spring. This enables elk to grow a complete new rack in just a few months.
The development of new antlers places a high demand on the elk’s nutritional resources. They require a significant intake of minerals, such as calcium and phosphorus, as well as protein, which are obtained through their diet. This ensures that bull elk are equipped with a fresh set of antlers each year, preparing them for the competitive demands of the next breeding season.