Reindeer, iconic inhabitants of the Arctic and sub-Arctic regions, are widely recognized for their impressive antlers. These unique bony structures are a defining characteristic. Unlike horns, which are permanent, antlers are shed and regrown annually, representing a significant biological investment.
Antler Shedding Cycle in Male Reindeer
Male reindeer typically begin growing their antlers in February, with growth continuing through spring and summer. By late summer or early autumn, around August, antlers reach maximum size, and the velvety skin covering them is shed, revealing hardened bone underneath. This prepares them for the rut, or mating season, which occurs in October and November. During this time, males use their large antlers to compete for access to females, engaging in displays of strength and physical clashes. After the rutting season concludes, most adult male reindeer shed their antlers in late autumn or early winter.
The Unique Antler Cycle of Female Reindeer
A distinctive feature of reindeer is that females also grow antlers. While generally shorter and less branched than those of males, female antlers can still reach lengths of up to 20 inches. Female reindeer typically begin growing their antlers later than males, around May. Females often retain their antlers throughout much of the winter, particularly if they are pregnant, which provides an advantage during harsh winter months. Pregnant females benefit from keeping their antlers, shedding them only after their calves are born in the spring.
Biological Purpose of Antlers and Their Shedding
Antlers serve several important biological functions for reindeer. For males, the primary role is in sexual selection and male-to-male competition during the rut. Large, robust antlers signal dominance and health, helping males attract mates and defend their harems. They also allow males to engage in ritualized combat, pushing and locking tines to establish hierarchy without causing severe injury.
For female reindeer, antlers are crucial for survival during the winter. They use their antlers to clear snow, a technique known as cratering, to access lichen and other vegetation buried beneath, which is a vital food source. Antlers also enable females to defend their foraging areas and protect food resources from other reindeer, especially important during pregnancy when nutritional needs are high. The annual shedding of antlers allows for the growth of new, often larger and more complex, sets each year.
Antler Regrowth and Annual Renewal
After antlers are shed, the process of regrowth begins, marking one of the fastest rates of tissue growth in the animal kingdom, with new antlers emerging from permanent structures on the skull called pedicles. During their growth phase, antlers are covered in a soft, fuzzy skin rich in blood vessels and nerves, known as “velvet.” This velvet supplies necessary nutrients and oxygen for rapid bone formation, with antlers capable of growing up to half an inch per day. As antlers mature and harden by late summer, the blood supply to the velvet diminishes, and it dries out. Reindeer then rub their antlers against trees and other objects to remove the dried velvet, revealing the solid bone beneath. This annual renewal ensures reindeer have a fresh, strong set of antlers each year for competition, defense, and foraging.