Elk antlers are used primarily for mating purposes, to battle other male elk for mating rights. Antlers require a great deal of nutrients and energy to grow; only the healthiest elk can grow large antlers. Hard antlers are comprised mostly out of calcium and phosphorus. This is because elk do not consume much calcium as part of their diet; therefore, the calcium in their antlers is produced by chemical reactions in their bodies, which draws heavily on the animal’s mineral reserves. Thus, the size of antlers is an external demonstration of an elk’s fitness.
Male elk grow their first set of antlers when they hit puberty, at approximately one year of age. Testosterone plays an important part of the antler cycle. The seasonal changes in the amount of daylight ultimately control the secretion of the reproductive hormone, testosterone, in males. Growth of antlers typically begins in spring, as testosterone levels increase in response to increasing day light. An elk’s antlers can grow at a rate of ¼ inch per day. In just four months, elk antlers are fully developed.
When the antlers are growing, they are soft to the touch or spongy. Unlike horns, which are keratinized tissue, antlers are organs. They have blood vessels, nerves, skin, cartilage and bone.
Antler growth is one of the fastest known types of tissue growth in mammals, and the only example of an organ that is shed and regrown each year.
Towards the middle of summer, the antlers reach their full size and the cartilage in the antler begins to calcify. By late summer, when testosterone levels are at their peak, the blood vessels shut down around the base of the antlers and the antlers harden into bone.
Hard antlers remain on the elk through the peak until late fall or early winter. As the deer’s testosterone levels drop off, the antlers are shed. Antlers are grown and shed every year.