Independence Runs in the Family
With tomorrow being the Fourth of July, I thought it would be appropriate to highlight an animal that symbolizes the spirit of resilience and freedom on which this country was built. This animal has walked across America since….well before the Ice Age, so a long time. It is my distinct pleasure to introduce you to the uniquely American, Pronghorn!
What is it? Do you remember the song “Home on the Range”? It talks about where the deer and the antelope play… well those antelope are actually pronghorns, also known as the American antelope. Despite looking similar to antelope and filling the same ecological job, pronghorns are not antelope….they aren’t deer either. They are the last surviving members of the Antilocapridea family, which were North American, even-toed ruminants (herbivores that get nutrition from a fermenting process before digestion. Like a cow). Surprisingly, their closest living relatives aren’t antelope or deer, but giraffe and okapi. Pronghorns get their names from their horns, that have a distinct branch, with one tine going forward (it’s the only horn that does this, and it is only in the males). They aren’t very large animals standing at 3.5ft at the shoulder and can weigh between 75-143 pounds. They live around 10 years out in the wild, but have been known to reach 15 years old in zoological settings.
Where are they found? ‘Murica…. Pronghorns are found west of the Mississippi and as far north as Alberta and Saskatchewan down into Mexico and the Baja peninsula. Pronghorns are, similar to Bambi’s dad, the kings of the prairie. They are found in browsing in grasslands, shrublands, and occasionally the desert. Similar to other speedy runners, pronghorns need wide open spaces to run, so they avoid areas with trees and other obstacles. Pronghorns are social and their social dynamics change with the seasons. In the winter they will form large mixed-sex herds, but with the onset of spring they break up into smaller herds. Females will form herds called harems, young males will form bachelor groups (like a fraternity), and adult males are solitary.
What do they eat? Pronghorns are herbivores, so they only eat plants. Their diet is mostly made up of grasses, shrubs, cacti, and forbs (I had to google this, they are flowering plants like sunflowers or clovers). Pronghorns are also able to eat plants that are uneatable or even toxic to domestic livestock. Pronghorns are usually found within a few miles of water but can supplement some of their water needs with vegetation that naturally holds a good amount of water.
What does Pronghorn dating look like? In the world of the pronghorns, courting is like a high school drama. Males have territories they mark using scent glands, urine, and vocalizations. They will fight for breeding rights if necessary. That’s pretty normal and you have probably seen this behavior in animal shows. What is high school about all this masculine Apostering, is that female pronghorns will do one of two things… either they will be chill and stick with one male through her entire cycle, OR females will travel around, sample different males, and then cause fights between the males. When it comes to actual courting, males will make cute little noises at her, create his musky goodness, and show off his handsome cheek patches by waving his head around for her to admire. So sweet. Gestation is around 7-8 months, and pronghorns commonly have twins.
What are the Pronghorns’ superpowers? Pronghorns are the fastest land animals in the Western Hemisphere and the second fastest land animal in the world. The only animal faster than a pronghorn are African cheetahs. Pronghorns can run 55mph for half a mile, and around 45mph for much longer, which may not be as fast as the cheetah, but they can maintain the speed for a longer time. Why are they so fast when the only predator fast enough to catch them is across the ocean? Remember when I said they’ve been around a long time? Well, the pronghorns are products of their time, and back in the day there was a super speedy predator called the American cheetah. Though the American cheetahs are no longer around, the pronghorns have kept their speed. To help evade predators, pronghorns have extremely large eyes and can detect movement up to 4 miles away. It would be hard to sneak up on these track stars.
How many Pronghorns are there? There is an estimated 750,000 to 1 million adults in North America. There are is some debate about the number of subspecies, and the main argument is if the subspecies is based off geographical or genetic differences. Genetically there are only three subspecies; the American, Mexican, and Baja California. In the Science section I will list the 5 geographical subspecies.
Image from Kauffman, et al. (2020). Ungulate migrations of the Western United States Vol. 1
Science Time (and the crowd goes wild!)
Pronghorn - Antilocapra americana
American pronghorn
Rocky Mountain pronghorn - A. a. americana
Oregon pronghorn - A. a. oregona
Mexican pronghorn
Mexican pronghorn - A. a. mexicana
Sonoran pronghorn - A. a. sonoriensis
Baja California pronghorn - A. a. peninsularis
According to the IUCN Red List Pronghorns are of Least Concern and in general they are stable. There are some subspecies, like the Sonoran pronghorn, that are facing an uncertain future with only 200-500 in Mexico and less than 300 in the US. The Mexican subspecies are protected under the US Endangered Species Act.
I can’t tell you how happy I am to say that the IUCN really only lists historic major threats of over hunting and loss of habitat, That’s not to say they don’t have threats at all. Current threats include food competition with livestock, road and fence construction, illegal hunting, and habitat fragmentation.
Resources:
International Environmental Library Consortium. (2024). Pronghorn (Antilocapra americana) fact sheet: Population & conservation. San Diego Zoo Alliance Library. https://ielc.libguides.com/sdzg/factsheets/pronghorn/bibliography
IUCN SSC Antelope Specialist Group. (2016). Antilocapra americana (errata version published in 2017). The IUCN Red List of Threatened Species 2016: e.T1677A115056938. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T1677A50181848.en
National Park Service. (n.d.). Pronghorn: Racers on the Great Plains. Wildlife in the Badlands. https://www.nps.gov/articles/000/pronghorn.htm
