Antlers, distinct from horns, are bone structures that grow and shed annually from a deer’s skull. Unlike permanent horns, antlers are living tissue that develop rapidly each year and are then discarded. Caribou are unique among deer species because both males and females typically grow antlers. These impressive cranial appendages serve multiple purposes, playing roles in dominance displays and foraging.
The Annual Cycle of Antler Shedding
Mature male caribou generally shed their antlers from late October through December, following the intense breeding season (the rut). This natural annual event occurs after males expend significant energy during mating. The timing can vary slightly depending on the individual’s condition and the specific caribou population. Once shed, the growth of a new set of antlers begins almost immediately.
Shedding is a deliberate biological process. A specialized layer of cells, the abscission layer, forms at the pedicle (the bony base connecting the antler to the skull). This layer weakens the connection, causing the antler to detach cleanly. After shedding, a soft tissue covers the pedicle, preparing for the next cycle of antler development.
Variations in Shedding Time
While mature males typically shed in late autumn, the timing of antler shedding varies significantly among caribou based on sex, age, and reproductive status. Female caribou retain their antlers much longer than males, often keeping them through the winter and into the spring. Pregnant females usually shed their antlers shortly after calving, typically in May or June, using them to defend calving grounds and access snow-covered forage. This extended retention provides an advantage during a vulnerable period.
Non-pregnant female caribou may shed their antlers earlier in the spring, sometimes in April. Younger male caribou tend to shed their antlers later than older, more dominant males, often retaining them until late winter or early spring.
The Purpose and Process of Antler Regrowth
Caribou shed antlers to grow a new, larger, and stronger set for the upcoming year. This annual renewal allows them to develop impressive racks valuable for establishing dominance and competing for mates. Larger antlers often signal better health and genetic fitness. Shedding also removes damaged antlers, replacing them with fresh, robust structures.
Following shedding, new antlers grow rapidly from the pedicles. During this growth phase, the antlers are covered in a soft, fuzzy skin called velvet, which is rich in blood vessels and nerves. Velvet supplies nutrients and oxygen for rapid bone formation. Once the antlers reach full size and harden (by late summer or early autumn), the velvet dries and is rubbed off, revealing the fully formed bone underneath.