Pronghorn, a unique North American mammal, are widely recognized for their exceptional speed, making them the fastest land animal in the Western Hemisphere. Their ability to run up to 55 miles per hour allows them to evade predators across their open, grassy habitats. Beyond their remarkable swiftness, pronghorn also possess distinctive headgear that often sparks curiosity.
The Pronghorn’s Distinctive Headgear
Both male and female pronghorn grow headgear, though the female’s is much smaller, sometimes appearing as only small bumps. Male headgear can reach lengths of 10 to 12 inches, featuring a forward-facing prong that gives the animal its name. This headgear is unique because it is neither a true horn nor a true antler.
Pronghorn headgear consists of a permanent bony core covered by a keratinous sheath. Unlike true horns, this outer keratinous sheath is shed annually in late fall or early winter for males. The annual shedding of a keratinous sheath from a permanent bony core, combined with its forked shape, makes pronghorn headgear distinct.
Differentiating Horns and Antlers
True horns are found on animals such as cattle, sheep, and goats. These structures are composed of a bony core covered by a keratinous sheath and are never shed. Horns are unbranched and grow continuously throughout an animal’s life. They are often present on both male and female individuals within a species, although male horns tend to be more prominent.
Antlers, in contrast, are characteristic of the deer family, including elk and moose. These are solid bony structures that grow as an extension of the skull. Antlers are branched and are shed and regrown entirely each year. During their growth, antlers are covered in a soft, vascularized skin called velvet, which supplies nutrients to the developing bone. Antlers are only present on males.
Purpose and Development
Pronghorn headgear serves multiple purposes for both sexes. It is used for defense against predators and in social displays. Among males, the headgear is important for sparring and establishing dominance during the breeding season.
A new keratinous sheath begins to grow beneath the old one, and this new growth aids in pushing off the older sheath. Males shed their sheaths between October and December, after the rut, with new growth completing by late winter or early spring. Females shed their sheaths later, in mid to late summer. Pronghorn headgear reaches its maximum size between two and three years of age, with growth influenced by nutrition and genetics.