Elk, members of the deer family, possess distinctive antlers that are unique among mammals for their annual cycle of growth and shedding. Unlike horns, which are permanent structures made of keratin, antlers are bone and are shed and regrown each year. This process allows male elk, or bulls, to regenerate bony structures that play a significant role in their social and reproductive lives.
The Timing of Antler Shedding
Elk typically shed their antlers from late winter to early spring, between February and April, with most falling off in March. The exact timing varies for individual bulls, influenced by several factors. Older and more dominant bulls often shed earlier than younger or less dominant ones.
A bull’s nutritional status also impacts the shedding schedule; a restricted diet can lead to earlier shedding, while poor nutrition might delay the process. Geographic location and climate also play a role. This annual shedding occurs a few months after the breeding season, known as the rut.
The Biological Reasons for Shedding
The primary physiological trigger for antler shedding is a drop in testosterone levels in male elk after the breeding season. This hormonal decrease leads to the formation of a specialized tissue layer, called the abscission layer, between the antler and the pedicle. Bone-dissolving cells, known as osteoclasts, become active within this layer, weakening the bony connection at the pedicle, the antler’s attachment point to the skull.
This degeneration is a rapid process, sometimes causing antlers to detach within one to two days. Shedding antlers provides an evolutionary advantage, allowing elk to grow new, larger and stronger antlers each year. This annual regeneration ensures bulls develop racks for display and competition during the breeding season.
The Antler Regrowth Cycle
After shedding, elk bulls begin regrowing a new set of antlers. This regrowth is fast, with antlers capable of growing up to one inch per day during their peak phase, making them one of the fastest growing tissues in the animal kingdom. During this period, developing antlers are covered by a soft, fuzzy skin called velvet.
Velvet is highly vascularized, containing numerous blood vessels that supply nutrients and oxygen for rapid bone formation. As antlers reach full size, typically by late summer, they undergo calcification where cartilage is replaced by hardened bone. Rising testosterone levels then trigger the velvet to dry up and shed, as its blood supply is cut off. Elk often rub their antlers against trees and shrubs to remove the drying velvet, which also polishes and strengthens the exposed bone for the rut. Once shed, these discarded antlers often become a source of minerals, consumed by rodents and other small animals.