Moose are distinctive for their imposing size and, in males, their expansive antlers. These bony structures can span up to six feet wide and weigh as much as 40 pounds, serving as a display of health and dominance. This annual cycle of shedding and regrowing antlers is a complex biological process driven by hormones.
The Annual Cycle of Antler Shedding
The shedding of moose antlers is a yearly event primarily triggered by hormonal shifts within the bull moose’s body. Following the autumn breeding season, known as the rut, testosterone levels in male moose decline as daylight hours shorten. This decrease weakens the connection between the antlers and the pedicles, bony protrusions on the moose’s skull. Unlike horns, which are permanent structures, antlers are solid bone and shed completely each year.
The weakening of tissue at the pedicle forms an abscission layer, causing the antler to loosen. The process is not painful for the moose, though it can cause some discomfort. Moose may rub their antlers against trees or shake their heads to help dislodge them, or they may fall off from movement. Shedding typically occurs in late winter to early spring, though the exact timing varies by location, age, and individual health. Mature bulls often shed earlier than younger ones, as carrying large antlers demands significant energy, and shedding conserves resources for colder months.
The Remarkable Process of Antler Regrowth
Following shedding, new antler growth begins from the pedicles. This regrowth is one of the fastest rates of tissue growth in the animal kingdom, with antlers capable of growing an inch or more per day and gaining up to a pound of bone daily during peak development. During this growth phase, developing antlers are covered in a soft, fuzzy skin called velvet. This velvet is highly vascularized, containing a dense network of blood vessels and nerves that supply essential nutrients and oxygen for rapid bone formation.
As antlers grow throughout spring and summer, they remain sensitive due to the velvet covering. By late summer or early fall, as the breeding season approaches, the antlers become fully calcified and hardened. The blood supply to the velvet then ceases, and it begins to dry and become itchy. Moose rub their antlers against trees and shrubs to scrape off the dead velvet, revealing the hardened, bony antlers beneath. This prepares the bull moose for the rut, where their antlers are used for display and competition.
The Afterlife of Dropped Antlers
Once moose antlers are shed, they become a valuable part of the ecosystem. These discarded bony structures are rich in essential minerals, particularly calcium and phosphorus. This makes them a sought-after nutritional supplement for various animals.
Rodents like mice, squirrels, chipmunks, and porcupines frequently gnaw on shed antlers to obtain minerals and wear down their continuously growing teeth. Other wildlife, including deer, raccoons, opossums, and coyotes, also consume parts of antlers. Over time, any remaining antler material decomposes, returning its mineral content to the soil and contributing to nutrient cycling. While some shed antlers are collected by humans, many are naturally recycled back into the environment, fulfilling an important ecological role.