For many, the image of a deer with impressive headgear brings to mind a male. The common understanding is that antlers are a characteristic feature of bucks, serving purposes related to breeding and dominance. However, the natural world often presents fascinating exceptions to general rules. Contrary to this widely held belief, some female deer can indeed grow antlers, though the circumstances vary significantly depending on the species and individual biological factors.
Antler Development in Deer
Antlers are distinct from horns. Antlers are true bone structures that grow as extensions of a deer’s skull, typically found only on males. Unlike horns, which are permanent and composed of a bony core covered by a keratin sheath, antlers are shed and regrown annually. This annual growth cycle is primarily influenced by hormones, particularly testosterone, and environmental cues like changes in daylight.
The process of antler growth is remarkably rapid. During their growth phase, antlers are covered in a soft, vascularized skin known as velvet. As the breeding season approaches, testosterone levels rise, causing the velvet to dry and peel away, revealing the hardened bone underneath. After the breeding season, a decrease in testosterone levels triggers its shedding, and the cycle begins anew the following spring.
Female Antler Bearers
While antler growth is generally a male trait in most deer species, there is one notable exception where females regularly grow antlers: reindeer, also known as caribou. In this species, both males and females develop antlers, although male antlers tend to be larger and are shed earlier in the year. Female reindeer typically retain their antlers through the winter, often shedding them in late spring after giving birth.
This unique adaptation in female reindeer is believed to be an evolutionary advantage for survival in their harsh Arctic environments. Their antlers are instrumental in foraging for food by digging through snow. Additionally, antlers help female reindeer compete for access to limited resources and establish dominance within herds, especially during pregnancy when maintaining nutrition is important.
Causes of Atypical Antler Growth
Beyond reindeer, the presence of antlers on female deer in other species, such as white-tailed deer, is an exceptionally rare occurrence. Estimates suggest it happens in approximately 1 in 10,000 female white-tailed deer. These atypical cases are attributed to biological irregularities. One primary cause is a hormonal imbalance, specifically elevated testosterone levels in the female, which can result from issues with the ovaries or adrenal glands.
Genetic anomalies, such as hermaphroditism where an individual possesses both male and female reproductive organs, can also lead to antler growth in deer that are appearing female. Injury to the antler pedicle, the bony base on the skull from which antlers grow, or even an injury to the deer’s testes (in cases of male deer mistakenly identified as females) can influence atypical antler development or retention. Antlers grown by female deer in these rare instances are often smaller, can be deformed or lack branching, and frequently remain covered in velvet due to insufficient testosterone levels for hardening and shedding velvet.