Antelope of the West, the pronghorn: WPWC

We recently returned from a long road trip through several western states and spotted hundreds of pronghorn along the way. I’m a big fan of this antelope of the west and love taking pictures of them.

Pronghorn, Antilocapra americana, also known as antelope or pronghorn antelope, are quirky animals in many ways. Their scientific name means “American goat-antelope.”

In September of 1804, upon first seeing pronghorn, Lewis and Clark expedition members assumed they were goats. Captain Lewis noted the “superior fleetness of this anamal which was to me really astonishing.” Upon examining them more closely, Lewis referred to them as antelope, based on their resemblance to African antelopes.

In reality, pronghorn are the only surviving members of the North American Antilocapridae family. Goats and true antelopes are in the Bovidae family.

In this post, I’ll share more about their natural history.

Range

Pronghorn range from the southern prairie provinces of Canada, southward into the western states of America and into northern Mexico.  

Identification & unique characteristics

Pronghorn are small ungulates (hoofed mammals), measuring 34 to 35 inches at the shoulder. They weigh 77 to 154 pounds. Reddish-brown fur covers their backs, sides, and neck. Their underbellies, inner legs, rumps, and the front of their necks are white. The males have a black mane, cheek patch, and forehead marking. Hollow guard hairs cover a layer of a shorter undercoat. When alarmed, pronghorn erect their rump hair, and this signal is visible from a great distance. Their horns have a short “prong” in the front, which gives them their name. The horns are modified, fused hair sheaths that form over a bony extension on their forehead. Unlike any other mammal in the world, the horn sheath is shed every year. Males and females can have horns, but the female’s are much smaller.  

Behavior & life history

In winter, pronghorn form large herds, and, in the spring and summer, smaller groups travel together. Young males form bachelor herds, while older males often wander alone, defending territories from others.   

Bucks defend small harems of does from March through the end of October. Sites with natural barriers, and more water sources, attract more does. Pronghorn have scent glands on their cheeks, between their hooves, on their rumps, and above their tails. The scent attracts mates and marks territory. If males feel threatened by another male, they will engage in a brief horn-horn or head-head battle.     

Northern populations breed from mid-September to October, while southern populations breed from July to October. The gestation period is 7 to 8 months. Initially, up to seven embryos form, but does give birth to single or twin fawns. Females eat the afterbirth and droppings of the newborn fawn to decrease the chance of predation. Fawns wean at around three weeks of age and remain near the females for 1 to 1.5 years. The average lifespan of pronghorn in the wild is 16 years.     

Pronghorn feed on grasses, shrubs, leaves and stems. Animals that prey upon pronghorn include wolves, coyotes, bobcats, cougars, jaguars, and golden eagles. They evade predators by running as fast as 37 to 40 miles per hour for long distances and 61 miles per hour in sprints. Pronghorn have a larger windpipe, heart, and lungs that help them process blood and oxygen better.     

After spending several field seasons at Hart Mountain National Antelope Refuge in the 1980s, I would use  one word to describe pronghorn: curious. They often follow visitors in their territory closely.

Habitat needs

Pronghorn live in grasslands, sagebrush steppe, and desert environments. They feed on grass, forbs, and shrubs. In the southern part of their range, they also eat cacti. Pronghorn are dependent on sagebrush for foraging in much of their range. Their habitat ranges from sea level to 11,483 feet in elevation. Pronghorn travel great distances to find water if the vegetation doesn’t have a high enough moisture content.  

Status & conservation

Prior to colonization, North America was home to 35 million pronghorn. Their numbers plummeted to 20,000 by 1924. Because of conservation efforts, they currently number between 500,000 to 1 million. Hart Mountain National Antelope Refuge, in southeastern Oregon, was established in 1936 as part of those efforts. The current population of pronghorn in Oregon is 25,000. A limited hunting season begins in August.   

 

Threats include unsustainable livestock grazing practices, insufficient water or food plants, poaching, and lack of recruitment. Natural and constructed barriers restrict their movements. Highways, rail lines, and fences may have significant effects on their populations. Pronghorn sometimes become fatally entangled in fencing.     

Energy developments also have negative effects. Gas, oil, wind, and solar developments can significantly affect pronghorn habitat. More recently, mining for the lithium needed for electric vehicles may damage preferred habitats.   

Two subspecies, the Sonora pronghorn and the peninsular pronghorn, are endangered.  

Interesting facts

• Unlike deer and elk, pronghorn generally avoid jumping fences, preferring to go under them. In some locations, efforts are underway to replace the lowest line on barbed wire fencing with smooth wires, making it easier for pronghorn to pass beneath them.
• Pronghorn often inhabit areas grazed by cattle, bison, horses, and domestic sheep. Pronghorn populations decline where sheep graze because of their preference for the same food plants.
• In the distant past, the now-extinct American cheetah lived within the pronghorn’s range. Pronghorn may have developed their fast speed to elude this and other predators.
• They feed on plants such as lichen and locoweed that are toxic to other ungulates. This may be because their liver is twice the size of a domestic sheep’s.
• Pronghorn’s enormous eyes, and 320-degree field of vision, allow them to detect movements as far as three miles away.
• This quirky animal’s I think the reason they are one of my favorite animals, is because they don’t quite fit in with others around them. Their differences are their strengths.

  Weekly Prompts Wednesday Challenge (WPWC) – Quirky