Deer are iconic animals, often recognized by the impressive bony structures that grow from their heads. While these structures, known as antlers, are commonly associated with male deer, there are rare instances where female deer can also develop them. Understanding this unusual occurrence requires a look into the biology of antlers and the factors that influence their growth.
The Nature of Antlers
Antlers are unique to the Cervidae family, which includes all deer species. These structures are made of bone, cartilage, fibrous tissue, nerves, and blood vessels, growing directly from bony outgrowths on the skull called pedicles. Unlike horns, which are permanent, made of keratin, and found on animals like cattle and goats, antlers are shed and regrown annually.
The annual growth cycle of antlers is rapid, with some deer species growing antlers as fast as 1.5 inches per week during their peak. While growing, antlers are covered in a soft, hairy skin known as “velvet,” which supplies essential oxygen and nutrients to the developing bone. Once fully grown, the velvet dries and is rubbed off, leaving behind the hardened, bony antler.
Antlers and Male Deer
Antlers are primarily a characteristic of male deer, driven by hormonal changes, particularly the levels of testosterone in their bodies. As testosterone levels increase, typically in late summer, it signals the antlers to harden and the velvet to shed. This hormonal regulation ensures that male deer have fully developed, hardened antlers in time for the breeding season, also known as the rut.
The main purpose of antlers for male deer is to establish dominance and compete for access to females during the breeding season. They use their antlers for display to signal their strength and health, and for direct combat with other males. Larger antlers can indicate age and genetic superiority, which may attract mates.
When Female Deer Develop Antlers
While male deer almost exclusively grow antlers, female deer can, on rare occasions, develop them. The most common reason is a hormonal imbalance, specifically elevated testosterone. Normally, female deer have very low testosterone, but endocrine system conditions can lead to an increase in this hormone, triggering antler growth.
Another less common cause for antler development in does can be an injury. Damage to the pedicles, the bony bases on the skull where antlers grow, can sometimes stimulate abnormal antler growth. Genetic anomalies are also a rare factor, where a female deer might have a predisposition to grow antlers. These antlered does often have antlers that are smaller, atypical in shape, or remain partially or fully covered in velvet because they do not experience the typical surge of testosterone needed for full hardening and shedding. Reindeer (caribou) are a unique exception, as both male and female reindeer regularly grow antlers.