Antlers are bony structures that grow from a deer’s skull, primarily on males within the Cervidae family (deer, elk, moose). Caribou are an exception, as both male and female caribou grow antlers. These important growths serve purposes like display, defense, and competition among males during the breeding season, known as the rut. Unlike permanent keratin horns, antlers are unique because they are shed and regrown annually.
The Yearly Antler Cycle
The annual antler cycle for deer begins in late winter or early spring. New antler growth starts shortly after the previous set has been shed, often in March or April, with tiny “buds” appearing on the pedicles. This initial growth is rapid, driven by increasing daylight hours and a rise in testosterone levels. Deer antlers can grow as much as a quarter-inch per day, while elk antlers can grow up to an inch daily.
During spring and summer, antlers develop rapidly, covered by a vascularized skin called velvet that supplies nutrients. By late summer, usually August or September, antlers reach their full size and begin to harden. The velvet then dries and is shed, revealing the polished, bony antlers underneath. These hardened antlers are carried through fall and early winter, aligning with the breeding season when they are used for sparring and establishing dominance.
Influences on Antler Development
The size of a deer’s antlers each year is shaped by several factors. Age plays a key role, as antler size generally increases as a deer matures, peaking between 4 and 7 years. Older deer might then see a decline. Nutrition is also crucial; access to high-quality forage rich in protein, calcium, and phosphorus supports strong antler growth. Deer in areas with abundant food sources produce larger antlers.
Genetics influence the potential for antler size and shape, with traits passed down from parents. Even with good nutrition, a deer’s genetic makeup sets the upper limit for its overall antler potential. Hormonal influences, particularly testosterone, regulate the antler cycle, from initiating growth to triggering hardening and shedding. These factors determine the annual development of a deer’s rack.
How Antlers Grow and What They Are Made Of
Antlers are bone structures that develop from specialized growth points on the deer’s skull called pedicles. These pedicles begin to form when a male fawn is only a few months old. During growth, antlers are covered by a soft, fuzzy skin known as “velvet.” This velvet is rich in blood vessels and nerves, providing the necessary blood flow, oxygen, and nutrients for rapid bone formation.
Antler growth is one of the fastest forms of bone growth in the animal kingdom. As antlers grow, cartilage is initially formed and then progressively replaced by bone tissue through mineralization. Once antlers reach full size and harden, the blood supply to the velvet diminishes, causing it to dry and peel away. This process leaves solid, calcified antlers, composed primarily of calcium and phosphorus, similar to skeletal bone. Unlike horns, which are permanent and made of keratin, antlers are true bone and are shed annually.
Antler Shedding and Regrowth
The annual shedding of antlers marks the completion of one cycle. This process is triggered by a decrease in testosterone levels after the breeding season, occurring from late December to early March. A specialized layer of cells, osteoclasts, forms at the base of the antler, near the pedicle. These cells break down the bone connection, weakening it until the antler detaches.
Once an antler is shed, the pedicle heals, forming a scab-like covering. This prepares the site for the growth of a new set of antlers in the upcoming spring. The shed antlers themselves are a source of minerals and are often gnawed on by rodents and other animals.