Pronghorn, known for their speed across North American plains, have a distinctive appearance due to their unique headgear. This feature often prompts a common question: do pronghorn shed their “horns” like deer shed antlers? The answer involves a fascinating biological process unique among mammals.
The Unique Nature of Pronghorn Headgear
Pronghorn headgear is unique among mammals, differing from both true horns and antlers. Often mistakenly called “antelope,” pronghorn are the sole surviving members of their family, Antilocapridae. Their head structures feature a permanent, bony core extending from the skull, similar to true horns. Uniquely, this core is covered by a keratinous sheath, which is shed annually. This tough outer layer is made of keratin, the same material found in human fingernails and hair.
The Annual Shedding and Regrowth Cycle
Male pronghorn shed their outer horn sheaths in late fall to early winter, following the breeding season. This shedding is triggered by hormonal changes, primarily a decrease in testosterone, which weakens the connection between the bony core and the keratin sheath. The old sheath then loosens and detaches, often pushed off by the new sheath growing beneath it.
After shedding, the permanent bony core remains attached to the skull. New sheaths begin to grow almost immediately over these cores. Initially, these growing sheaths may appear soft and covered, somewhat resembling velvet on growing antlers, though their underlying structure differs. These new sheaths harden over several months, developing their characteristic black color and shape. Their specific shape and size can vary slightly from the previous year, influenced by nutrition and environmental conditions.
Distinguishing Pronghorn Horns from Antlers and True Horns
Understanding the differences between pronghorn headgear, antlers, and true horns provides important context. Antlers, found on deer, elk, and moose, are composed entirely of solid bone. These structures are shed completely from the skull each year, typically after the breeding season, and then regrown. Antlers are often branched and generally found only on males, with the exception of caribou.
In contrast, true horns are permanent structures characteristic of animals like cattle, sheep, goats, and bison. They consist of a bony core that grows from the skull, covered by a keratinized sheath. Unlike antlers, true horns are never shed and continue to grow throughout the animal’s life. They are typically unbranched and can be present in both males and females, depending on the species.
Pronghorn headgear represents a unique evolutionary path, combining aspects of both. Like true horns, they possess a permanent bony core, but like antlers, they shed their outer covering annually. Male pronghorn headgear also features a distinct forward-pointing prong, giving the species its name.