Pronghorn Do the Strangest Things
Given the wide-open country they call home, coupled with their amazing speed (clocked at 60 mph, some claim as fast as 70 mph), it’s not surprising the pronghorn is considered a wild wanderer by most hunters. Here today, gone the next minute, never to be seen again. Zippiddy do-dah.
Reality is something different. Under most conditions, pronghorns are homebodies reluctant to leave their territories, which may be as small as two square miles. Some ranchers might say as small as an 80-acre alfalfa field, so regularly do these animals feed and bed in such choice locations. If the living is easy and they aren’t harassed, antelope (as they’re commonly but inaccurately called) like staying close to home. And this makes them fairly easy to hunt.
According to researchers, when food and forage are abundant, pronghorn females and their fawns join with a few others in summer to form tightly knit bands that use the same grounds over and over. The better the living conditions, the smaller the area they use. Water and food are the two essentials. By minimizing travel and knowing their territories intimately, they are best able to avoid predators. Drought, poor forage and dried up water holes force them to move great distances and expand their territories. Desert pronghorns may inhabit a hundred square miles.
Bucks respond to doe bands by staking out territories of their own, usually along the fringes of several doe groups in prime habitat. In this way they maximize contact with the most potential breeding partners come “the season.” The oldest bucks generally claim and defend the largest territories while youngsters flit around and between them as best they can.
A territorial buck marks it property by scraping a bare spot in the dirt and scenting it with urine and droppings. He also rubs oil from his black, odoriferous “cheek patch” glands on prominent twigs, yucca leaves, and shrubs. Finally, he stands on ridges and flat, broad fields for long periods, snorting and displaying to all that hear and see him. This snort-wheeze can be heard from as far as a mile on calm days and helps hunters locate their quarry. If you discover a concentration of bare, pawed ellipses of dirt with droppings in them, you’ve found a buck’s territory.
In poor habitat, bucks expand their territories, too, and if does begin to wander vast distances, bucks skip territorial defense and attach themselves to a particular doe group. That way they’re with them when breeding commences. No fear of arriving too late to the party.
During hunting season, when mating is usually underway, bucks will be running with the ladies. Some bucks switch from band to band within their territories while trying to keep interloping males out. Others stick with one band and merely defend them from encroaching males. Either way, hunters see a lot of chasing.
This behavior makes it possible for bowhunters to pop-up pronghorn buck decoys and bring harem bucks on the run, ready to fight. This works best early, before the first doe reaches estrus. For their part, does incite chases by showing interest in other bucks. This is to their genetic advantage because they then select the fastest, most durable buck for mating, ensuring strong, fast fawns.
One oddity biologists have discovered is the “hider” buck. This is a crafty devil that drives an estrus doe from the herd and into an obscure corner where they can enjoy a quiet honeymoon. In this way he prevents other bucks from stealing his girl. This tactic seems most common in tough, poor forage years when reduced chasing and fighting save energy.
Fighting? Oh yes, pronghorns fight just as vigorously as other horned males. Instead of bashing heads like sheep, they lock horns and wrestle. It’s mostly a twisting and shoving match, the loser getting escorted far away at the point of the winner’s horns – fast. It’s not unusual to find grooves, rips and stab marks where a buck has taken the brunt of an enemy’s horned attack. It is speculated that the prongs on antelope horns evolved to stop the forward progression of combatants’ horns, thus preserving eyes during the wrestling. The curved tips probably minimize dangerous stabbing wounds. By the way, pronghorns are the only horned animal that has a divided or bifurcated horn, which puts it in a family all its own. They are not true antelope, but the last survivor of an ancient family, Antilocapridae. Fossils show many variations that have gone extinct, including one with four horns, another with anvil-topped horns.
The final trait that clearly pushes pronghorns into a family all their own is the annual horn shedding. This is the only horned animal on Earth that ejects its horns and grows fresh ones. Here’s what happens: When testosterone levels drop after the rut, other hormones signal the outer sheath of horn to loosen from the core and fall off, usually around early November. This leaves a bony, four- to six-inch core with a black, rubbery cartilage covering. From this the new horn is already growing (as modified hairs that fuse together into a tough keratin similar to hooves) and continues through winter. By June it is pretty much done. This means winter conditions determine horn size. The easier the winter and more abundant food supplies, the bigger horns can grow. After age three, pronghorn bucks can maximize horn size with the right conditions. Most antlered game reaches biggest trophy potential at ages five through nine. And most horned game peaks at ten or more, since regular horns never stop growing. By shedding its horn sheath every year, the pronghorn compromises overall horn size.
Yup, the North American pronghorn is certainly an oddball. But it’s our oddball and we are privileged to get to hunt it.