Although often called antelope, pronghorn are not true antelope. In fact, they are the only living member of the family, Antilocapridae. In times past this group contained many species, some sporting multiple and bizarre horns.
The pronghorn is the ‘real' Great Plains large mammal. Although we often associate bison with rolling prairies, they are more adapted for living in woodland habitats than the American pronghorn. In fact, the pronghorn has never found subsistence outside the High Plains and sagebrush flats of the American West.
Although often called antelope, pronghorn are not true antelope. In fact, they are the only living member of the family, Antilocapridae. In times past this group contained many species, some sporting multiple and bizarre horns.
Highly advanced over any local natural predator, pronghorns puzzle researchers. Why such fleet feet? How does this fit into the ‘natural selection' theory? Some have postulated their speed evolved over time. In ancient times, these scientists theorize, there were many large and fast predators in the American West. However, due to unknown causes, they became extinct. Seems a bit unusual. Prey outliving the predator.
Undoubtedly, the most unique pronghorn attribute is their speed. Although running is their last defense, they are the world's fastest land animals. They can sprint up to 60 mph and sustain 30 mph for miles. In fact, although a cheetah could outrun them in a hundred-yard dash, the pronghorn would prevail in anything longer.
A running machine, the pronghorn has four different high-speed gaits. When fully extended the animal takes about three strides per second, covering up to 30 feet per stride. Strong herd instinct keeps the animals running together in a tight oval formation, much like a flock of birds. Even more amazing, they maintain a 97% gait synchronization and a 92% lead foot synchronization. This nimble dance works to confuse their predators.
Their swiftness has become legendary. Arthur Einarsen, in his 1948 book, The Pronghorn Antelope And Its Management, records an event he says occurred one day while he and two companions were driving through their Oregon study area. He writes,
"On August 14, 1936, I was with a group that paced many pronghorns on the dried bed of Spanish Lake in Lake County, Oregon. This lake bed was as hard as adobe. It was a clear, breezy day...ideal to stir the racing instincts of the pronghorns, and as we rolled along the lake edge we had many challenges. Small groups here and there raced beside the car, until five, led by a magnificent buck, ran parallel to us, pressing toward the shore from the feeding area in the lake center while we drove on a straight course. As they closed in from the right, the buck took a lead of about fifty feet and Myers increased speed to keep even with the animal. Dean Schoenfeld watched the speedometer, Myers drove the car, and I photographed the moving animals. The buck was now about 20 feet away and kept abreast of the car at 50 miles per hour. He gradually increased his gait, and with a tremendous burst of speed flattened out so that he appeared as lean and low as a greyhound. Then he turned toward us at about a 45 degree angle and disappeared in front of the car; to reappear on our left. He had gained enough to cross our course as the speedometer registered 61 mph. After the buck passed us, he quickly slackened his pace and when he reached a rounded knoll about 600 feet away, he stood snorting in graceful silhouette against the sky as though enjoying the satisfaction of beating us in a fair race."
Although later researchers discount Einarsen's story, the pronghorn's racing instincts and their tendency to cross in front of a rival as if to brag, has been recorded by many. I have ‘raced' many pronghorn while traversing the Centennial Valley's sagebrush flats and rolling hills. They seem to exult in their racing skills.
Why can the pronghorn run so far so fast? J.A. Byers, who studied these animals for twenty years, described them as "four-chopsticks-in-a-bratwurst." Their unique body type allows them to use 13 different gates from a very slow diagonal walk to a lateral gallop. However, it makes them very inept at jumping. If confronted with a barrier, they prefer to crawl under. If they must jump, they land on their back legs in a peculiar fashion.
Their long skinny legs are lightweight but strong. Their long stride is due to their front legs' extreme ‘pushed-back' position which allows a criss-cross action between their front and rear legs. Their superficial flexor tendon, which corresponds with our Achilles tendon, is unusually long. This allows their main body muscles to produce a high degree of torque in their lower legs.
To complete their striking design, they have a straight back. Instead of flexing with each stride like the Cheetah, their backs stay more rigid, similar to a horse. They carry their heads upright; not stretched out in front. Their advanced visual system also plays a key role as they travel on skinny legs at high speeds over broken ground.
A pronghorn's eyes are about two inches in diameter, the largest in the mammal world. They possess wide peripheral vision. They can spot movement three miles away. Because their eyes are located far back on their head, they can even keep a lookout while grazing.
None-the-less, their body structure would be nothing less than an awkward incumbrance without a customized power system. Here, again, they are unusual. Take their heart. The pronghorn's heart is twice as large as that found in a similar-size domestic goat. It pumps 50% more blood. It produces 60% more hemoglobin, the protein in the red blood cells which carry oxygen. It contains 33% more red blood cells, the vehicles which deliver oxygen and remove carbon dioxide throughout the body.
In addition, the pronghorn's windpipe is super-sized. A human's windpipe is about 3/4" in diameter. A mature pronghorn's is 2" in diameter. If pressed, the animals will even allow their tongues to hang out for better air flow.
Their lungs are three times larger than those found in a comparable goat. Their livers are large and can provide quick glycogen boosts which provide access to additional short-term energy.
Still, their body structure and super-powered engine would be useless without an operating system capable of functioning at high temperatures. Here, again, their makeup is superior. Their brain boasts four ‘heat-exchangers' which prevent it from overheating. These are located on their faces near their eyes and in their nose and ears.
So, what natural predator can harm such a highly adapted animal? Man.
It is estimated 35 - 50 million pronghorn once roamed the prairies from Saskatchewan to northern Mexico. Many believe they were more numerous than bison. By 1915, only about 12,000 remained. Today, however, they number between one-half to one million, most living in Wyoming and Montana.
In spite of their unusual body design, supercharged power structure, and advanced cooling system, a small Yellowstone herd may exhibit the species' most remarkable characteristic. Healthy numbers in other herds fail to reflect the Yellowstone herd's 50 percent population decrease. In fact, they now comprise less than 250 animals. What predator is having such a devastating effect? Again, man. This time in a less explosive but none-the-less devastating manner.
This undistinguished band makes a very distinguished annual trek from Yellowstone's southern regions to the Pinedale Mesa. This exodus comprises the longest terrestrial mammal migration between Argentina and Canada.
Research has shown six of the eight historic migration routes used by the Yellowstone pronghorn herd have vanished. You may yawn. What's the big deal? They'll change routes. Not so, says Joel Berger, a senior scientist with the New York-based Wildlife Conservation Society. His research shows, ". . . in the case of the pronghorn . . . the route is invariant and apparently has been that way for some 6,000 years."1
Moving three to twelve in a group and covering up to 30 miles per day, the pronghorn winter migration to the Pinedale Mesa takes only a few days. However, those who fail to migrate die.
In the spring they return along the same route. This migration can take up to a month as the animals follow the receding snow.
Natural land formations already create formidable barriers they annually traverse. Take the "Red Hills Bottleneck." On a steep slope squeezed between an impassible cliff band above and dangerous rapids below, the migrating herd's hoofs have carved a narrow track. "These animals literally come over the same hoofprints year after year," Kim Berger noted. 2
Joel, along with his wife, Kim, a wildlife biologist, have been studying the situation facing this special herd for several years. They have been using radio-tracking collars to obtain detailed information on travel routes and patterns. They have documented fawn survival rates. They have researched predator and weather impacts. Their studies are revealing what could be a grim prognosis for the Yellowstone herd.
The migration route is under attack - what some might call under ‘development'. As the oil and gas boom expands, housing and land developments keep pace. "The rate of housing increases at the southern terminus of the migration route is in direct proportion to the number of gas wells that are being drilled," Berger said. 3 "With more people, there is more habitat loss, and unless some safeguards are put in place, Wyoming's wildlife will lose." 4
Considering their speed-specific defense system, it comes as no surprise pronghorn do not like to go places where they can't see far and run fast. Unfortunately, human development has created bottlenecks along their migration routes which vary from 328 to 2000 feet wide. In other places the routes are blocked. Since they are not built for jumping, even poorly designed fences can close a migration route. And, as the Bergers have pointed out, the animals don't seek an alternate route. They just stop migrating.
The Bergers recognize oil and gas development is important. It has been estimated there are at least 20 trillion cubic feet of methane gas near the Pinedale Mesa. Natural gas. For a year. For an entire country! Not a small issue considering today's high energy demands.
None-the-less, without wise planning and strategic development, the Yellowstone pronghorn will be the one to lose. That doesn't have to happen.
Their predictable nature could make disaster easier to prevent. If the animals varied their route from year to year, it would be much harder to define specific conservation areas. But because their migration routes are so invariable, the animals are more vulnerable and yet should be easier to protect.
The Bergers have been working on a multifaceted approach to the problem. They have pinpointed critical areas - bottlenecks where further development would shut down migration routes. They have done behavioral studies to determine the increased physical ‘cost' on the animals from new development. They have provided information to resource management agencies, key private landholders, and local conservation organizations, seeking to cultivate cooperation.
In 2003, they proposed the nation's first National Migration Corridor. The proposed corridor is 90 miles long by 1 mile wide. It would provide protection for the lands therein, preventing further development.
Much like the big game corridor which the Greater Yellowstone Coalition and local conservation organizations are working to develop from Yellowstone National Park to Glacier National Park, many animal species benefit. In Wyoming's case, the pronghorn are the obvious winners. However, in both situations these corridors serve elk, deer, moose, and other mammals.
The solution seems within our grasp. The proposed National Migration Corridor lies almost completely on federal property. The proposal enjoys strong support in Teton County. However, Sublette County has given the idea lackluster support, and Wyoming's Congressional delegation, whose support is mandatory, is no more than lukewarm to the plan.
Maybe this is because Wyoming already has more antelope than people. In addition, the oil and gas industry is key to the state's economy. Maybe some of the independent spirit so key to the development of the American West is at work.
As an independent spirit and private landowner, I understand the repulsion to more federal regulations. However, recognizing our responsibility to care for and steward the animals our Creator has placed under our care, I would hope with creativity, cooperation, and properly placed concern, this problem can be dealt with resulting in a win-win situation.
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