Deer antlers are bony structures that grow from the heads of male deer, known as bucks. These formations are not permanent but are grown and shed annually, making them unique among mammals. Antlers serve various purposes, including establishing dominance and competing for mates during the breeding season.
The Annual Antler Growth Cycle
Male deer embark on their annual antler growth cycle in late March or early April. Small bumps called pedicles emerge from the deer’s skull. These developing antlers are covered in a soft, vascularized skin known as “velvet,” supplying oxygen and nutrients for their formation. During late spring and summer, antlers grow quickly, with some mature bucks experiencing growth rates of up to 1.5 inches per week.
By late summer, typically in August, antler growth slows significantly, and antlers begin to harden and mineralize. By late August or early September, blood flow to the velvet ceases, causing it to dry and itch. Deer rub their antlers against trees and brush to remove the dead velvet, a process that can take less than 24 hours. Once the velvet is shed, the antlers are fully hardened and polished, ready for use during the autumn breeding season, or rut.
What Influences Antler Development
Several factors influence the timing, size, and development of male deer antlers. Age is important, with yearling bucks (1.5 years old) growing their first noticeable antlers, varying from spikes to multi-pointed racks. Antler size generally increases with age, peaking around 6.5 years before potentially declining in very old deer.
Nutrition is a key determinant, as antler growth is a demanding process requiring sufficient amounts of protein, minerals such as calcium and phosphorus, and energy. Deer with access to high-quality forage and nutrients tend to develop larger antlers. Genetics also contribute to antler potential, influencing characteristics such as shape, composition, and size, though optimal nutrition is necessary for a deer to reach its maximum genetic potential.
Health and environmental stressors, such as injury, disease, or harsh weather conditions, can impact hormone levels. This can affect antler development or even cause early shedding.
Shedding and Regrowth
After the breeding season concludes, typically from late December through early March, male deer shed their antlers. This annual shedding is triggered by a decrease in testosterone levels, which occurs as daylight hours shorten. The decline in testosterone activates specialized bone-resorbing cells called osteoclasts at the base of the antler, at its connection to the skull.
These osteoclasts break down the bone tissue at the “abscission line,” weakening the connection between the antler and the pedicle, the permanent bony protrusion on the skull. The antlers detach, a process that can occur rapidly, sometimes within 1-2 days. Immediately following shedding, the pedicle forms a scab-like covering, and new antler growth begins, continuing the annual cycle.