The color of a reindeer’s antlers changes dramatically depending on its stage in the annual growth cycle. These bony extensions, which both males and females of the species Rangifer tarandus (reindeer or caribou) grow and shed annually, can appear dark red-brown, white, or various shades of gray. The difference in color is directly related to whether the antler is a living, growing organ or a fully hardened, dead bone structure.
The Appearance of Hardened Antlers
The antlers visible after the outer skin has been shed are fully grown, mature structures. At this stage, the antler is composed of dead, calcified bone, containing high amounts of calcium and phosphorus. Because this structure is no longer living tissue, it lacks any blood supply and naturally appears in shades of pale gray, white, or light bone-color.
The final appearance is often modified by the reindeer’s behavior and environment. As reindeer rub their hardened antlers against trees and shrubs to polish them, they pick up stains from the surrounding vegetation. This rubbing often imparts a light to medium brown or reddish-brown hue to the surface. The specific environment can influence this color, with forest-dwelling reindeer sometimes having darker antlers compared to mountain-dwelling populations.
Color During the Velvet Stage
Before the antler hardens, it is a living, developing organ covered in a layer of skin and fine hair known as “velvet.” This velvet is dense with blood vessels and nerves, supplying the massive amounts of oxygen and nutrients required for rapid growth. Antlers can increase by up to two centimeters per day during the peak season.
The dense network of blood vessels beneath the thin skin gives the growing antlers a distinctly dark appearance. This dark coloration is a direct result of the living tissue and high blood volume, often appearing reddish-brown, dark brown, or blackish. Once the antler reaches full size, the bone calcifies, cutting off the blood supply to the velvet, which then dries out. Reindeer strip this dead, itchy velvet off by rubbing their antlers vigorously against objects until the bone is cleaned and polished.
The Seasonal Cycle of Antler Shedding
The change in antler color from dark (velvet) to pale (hardened) is directly tied to the reindeer’s annual hormonal and reproductive cycle.
Male Antler Cycle
Males begin growing new antlers in late winter or early spring. They shed the velvet to reveal the hardened bone in late summer or early autumn, just before the mating season, known as the rut. After the rut concludes, dropping testosterone levels trigger the shedding of their fully hardened antlers, typically around November or December.
Female Antler Cycle
The timing is different for females, which are the only female deer species to regularly grow antlers. Most female reindeer retain their hardened antlers throughout the entire winter. They typically shed their antlers only after giving birth to their calves in the spring. This means that dark, velvet-covered antlers are primarily seen during the summer growing season, while pale, hardened antlers are visible in autumn and, for females, throughout winter.