Pronghorn Antelope Facts: History, Habitats and Habits

And now we come to the unique horns of the pronghorn, learn more about horns with these pronghorn antelope facts.

Unique pronghorn horn characteristic No. 1: The pronghorn
is the only ungulate to grow headgear that’s classified as
horn but which is forked–sort of. A mature pronghorn
buck will have horns a foot or more in length (up to a
maximum of 20 inches or so), with the tips curled back
(enabling rutsparring bucks to strike up into the
vulnerable throats of their rivals) and each with a single
flat prong, called the cutter, jutting forward from about
midway up the shaft (and serving much like the hilt on a
sword, to catch and stop the thrusting horn of a rival).
Does of the species sometimes have much smaller horns.

Unique pronghorn horn characteristic No. 2: The pronghorn
is the only ungulate to grow headgear that’s classified as
horn but which is deciduous–sort of. Each year,
between late October and early December, pronghorn bucks
shed the outer sheaths of their horns while retaining the
slender inner cores, around which new sheaths have already
begun to form. (In fact, the outward and upward pressure
exerted by the growing sheaths helps to loosen the old
sheaths.)

Unique pronghorn horn characteristic No. 3: hairy horns. On
my desk before me now I have the pronghorn horn from my
collection (a specimen I obtained, to my wife’s disgust, by
carving it from the crushed skull of a truck struck buck
alongside a remote Western byway several years ago). An
inspection of the base of the horn reveals three distinct
layers in cross section. The core, as with all horn, is
porous bone marrow. Around this core is wrapped a layer of
tough, white, cartilaginous tissue. The third, or outer
layer looks a lot like thick hairs stuck together with
black glue and hardened. Of course, as with most things in
life, there’s more to it than meets the eye.

The exterior of the horn I have here has a rough, barklike
texture except at the tip, which the buck had polished
smooth before his untimely demise. Under a magnifying
glass, individual, unfused blond hairs can be seen
protruding from the hardened black surface, more so near
the base, making for, in appearance at least, a hirsute
horn. What doesn’t meet the eye is the fact that the bulk
of the hairy-looking sheath is composed, not of fused hair,
but of cornified, or hardened, tissue called epithelium.

The pronghorn is unique in more than its horns. Giving the
lie to its scientific name, Antilocapra americana –literally, “American
antelope-goat”–the pronghorn in fact is no antelope
at all, nor a goat (though it is commonly called a prairie
goat by Westerners), but a unique, exclusively American
animal (length of residency: 20 million years) with no
close relatives of any sort anywhere on earth. Further,
it’s the sole genus in its scientific family,
Antilocapridae, and the sole living species in its genus.
(As opposed, say, to the deer family, Cervidae, which
comprises deer, elk, caribou and moose in North America
alone.)

An exceptionally large pronghorn buck might weigh as much
as 140 pounds, but the average is closer to 110; does run
about 10% lighter. The typical pronghorn stands to around
36 inches at the shoulders and is perhaps 52 inches in
length. The backs and upper sides of adults are tan to
russet, accented with thick dark manes, black facial
markings (on bucks only) and white belly, rump and throat
bands. The white rump is part of yet another unique
attribute of the pronghorn.

In the third volume of his classic Lives of Game
Animals, turn-of-the-century naturalist Ernest
Thompson Seton details how he determined, through physical
examination and dissection of dead zoo specimens as well as
lengthy observation of the living, that the pronghorn uses
its hoary posterior as a unique means of communication:

“[The white rump] seems at first like the rest of his
spots–a mere patch of white coat; but it is found to
be specialized for an important service. It is composed of
hair graded from short in the centre, to long at the front
edges. Under the skin of the part is a circular muscle by
means of which the hair can, in a moment, be raised and
spread radially into two great blooming twin
chrysanthemums, more or less flattened at the centre. When
this is done in the bright sunlight, they shine like tin
pans, giving flashes of light that can be seen farther than
the animal itself, affording a conspicuous identification
mark that must be of great service to the species.

“Seton goes on to explain that the first pronghorn in a
herd to spot potential danger will flash a warning,
simultaneously releasing a musky scent. These dual alarms
are quickly picked up by the rest of the animals, each of
which duplicates the alerts so that, in an instant, the
entire band is warned and on the lookout.

In pre-Columbian times, the pronghorn was one of the most
plentiful, possibly the most plentiful, of the ungulates
roaming North America, sharing the vast native grasslands
of Western and mid-America with the bison and ranging as
far east as the Mississippi River Valley. Seton once
estimated that in primitive times North America may have
hosted as many as 20 million pronghorns, but later
discounted that figure, deciding that it was “a very
low–a-far too low–estimate.” An earlier
researcher–publisher, naturalist, ethnologist arid
Audubon Society founder Dr. George Bird
Grinnell–speculated that pronghorns might even have
outnumbered bison, which are thought to have been some 40
million strong around 1800. In 1908, the U.S. Biological
Survey estimated that no more than 20,000 pronghorns
remained in all of Canada and the contiguous 48 states. But
the low point was yet to come: By 1915, the total had
dwindled to under 15,000. Miraculously, by the early 1920s,
primarily because of a total ban on pronghorn hunting
nationwide and the establishment of game preserves, the
population had more than doubled to an estimated 30,326,
including Canada and Mexico (Nelson, 1924).

Today, depending on where you live and travel, the
pronghorn can be plentiful enough to be considered an
agricultural pest and a hazard to nighttime motoring (near
Casper, Wyoming, for example, it’s common to see
trophy-size bucks lying within yards of busy highways,
insouciantly chewing cud while big diesel rigs scream
by)–or can be an almost mythological creature whose
name you may have heard in corny old cowboy songs but which
you aren’t likely to see outside a zoo. Pronghorn country
is dry country, much of it desert.

Where surface water is available, pronghorns will troop in
to drink deeply at least once a day. Where surface water is
insufficient or nonexistent, the remarkable animals
apparently can wring enough moisture to survive from
cactus, which plants can account for more than 10% of their
total diet, the rest consisting of grasses, forbs and
browse. The pronghorn, as an old-line denizen of the
treeless plains, prairies and deserts, has evolved to rely,
not on the natural camouflage and stealth employed by deer
and elk to keep themselves out of harm’s way, but rather on
its exceptional speed and vision. On September 17,1804, on
the westbound leg of his long trek to the Pacific with
William Clark, while traveling through what today is South
Dakota, Captain Meriwether Lewis recorded in his journal
the following observations (the creative spelling,
punctuation and capitalization are his):

“I had this day an opportunity of witnessing the agility
and the superior fleetness of [the antelope] …. I had
pursued and twice surprised a small herd of seven . . .
[and] got within about 200 paces of them when they smelt me
and fled; I gained the top of the eminence on which they
stood, as soon as possible from whence I had an extensive
view of the country.. . the antelopes which had disappeared
in a steep ravine now appeared at the distance of about
three miles on the side of a ridge …. so soon had these
antelopes gained the distance at which they had again
appeared to my view I doubted at first that they were the
same that I had just surprised, but my doubts soon vanished
when I beheld the rapidity of their flight along the ridge
before me . . . it appeared rather the rapid flight of
birds than the motion of quadrupeds. I think I can safely
venture the assertion that the speed of this animal is
equal if not superior to that of the finest blooded
courser.”

Well, yes, Cap’n, at the least: A prime buck pronghorn was
clocked in the 1940s by a researcher–an
unquestionably credible reporter who paced the animal in an
automobile–at more than 61 miles per hour. That is,
the car was doing 61 per when the pronghorn passed it. More
recent clockings have exceeded even this, with one report
claiming 70 miles per hour. Such speeds, of course, were
attained in brief sprints; in the long run, a pronghorn can
maintain more or less 40 miles per hour, mile after mile,
hour after hour. The best racehorses can approach that
speed but, lacking the pronghorn’s stamina, will blow gut
early on. In short, the pronghorn is the swiftest mammal
native to North America, the swiftest mammal in the
Northern Hemisphere and the second-swiftest mammal in the
world, following close on the heels of the cheetah (which
it will overtake and pass after the cat’s limited endurance
plays out).

The most colorful description I’ve seen of the pronghorn’s
visual acuity was reported in 1890 by Arthur W. DuBray and
retold in Animals of the World (1917):

“‘Liver-eating Johnson,’ guide, scout, hunter and trapper,
prairie-man, Indian fighter, thoroughly educated and
equipped frontiersman at every point, graduate at the head
of his class in prairie lore–withal, a long-headed,
cool, and calculating man–once said to me while
hunting: `What a live Antelope don’t see between dawn and
dark, isn’t visible from his standpoint; and while you’re
a-gawkin’ at him through that ‘ere glass to make out
whether he’s a rock or a Goat, he’s acountin’ your
cartridges and fixin’s, and makin’ up his mind which way
he’ll scoot when you disappear in the draw for to sneak up
on ‘im–and don’t you ferget it.’ ”

Tolling, also called flagging, will sometimes lure in a
wary buck.

In less colorful but more precise words, the pronghorn’s
big, black, long-lashed, protuberant eyes give it almost
complete wraparound vision and a magnification long hailed
as equal or superior to what you and I can see with the aid
of 8X binoculars. (Although I’m not sure how this
determination was arrived at.)

Given such amazing vision and speed, plus miles and miles
of miles across which to see and flee, the pronghorn’s
security would seem almost invincible. But both Meriwether
Lewis and Liver-Eating Johnson (who, incidentally, was the
flesh-and-blood mountain man on whose life and considerable
legend the Robert Redford movie Jeremiah Johnson was
based; the livers he purportedly ate were those of his
slain enemies) knew that the pronghorn had one fatal flaw
in its defenses: curiosity. Noting this, early white
hunters borrowed from the Indians a technique for using the
pronghorn’s unbounded curiosity to lure it to within rifle
range. Lewis called the trick “tolling,” while the
liver-eater knew it as “flagging.

“By either name, the caper required the hunter, after
spotting the distant white specks that mean pronghorn on
the prairie, to secrete himself in good cover, most often a
ravine or a clump of sagebrush. He would then attach a
brightly colored scarf to a long pole or the muzzle of his
rifle and wave it furiously overhead–or simply lie on
his back and kick his feet in the air. Spotting the
movement from a great distance, the fatally curious animals
would ease ever closer to the wondrous enticement. Whatever
could this odd dancing thing be? When the animals were
within range, the hunter took up his rifle and, if his aim
was true, had meat for the camp pot. (Which meat, by the
way, is–if the animal is killed cleanly and quickly
cooled–tender and delicious, tasting to me like a
cross between lamb and elk.) Savvy wildlife photographers
today use the same trick to entice shy ‘lopes into camera
range.

It’s just as well for pronghorns that they are such timid
creatures, for there are those who would have them for
dinner, and others who would exterminate them as pests.

Foremost among the pronghorn’s natural enemies is deep
snow, which slows and can even halt the small-hooved
animal’s escape from predators, buries his food and
generally makes life miserable. Parasites and disease also
take their toll. Important predators historically included
mountain lions and bobcats, bears, wolves, coyotes and
golden eagles (baldies prefer angling to hunting). Today,
coyotes–which know to run a prong horn in relays
until the sly dogs tucker out their far swifter
prey–still take the odd animal, and the golden eagle
remains a threat to newborn kids. Wolves, bears and
mountain lions, however, have fairly been extirpated across
the pronghorn’s vast arid range, much of the “wild” in the
once-Wild West disappearing with them.

The pronghorn’s primary enemies these days are you and I.
Although unrestrained hunting was a significant
contributing factor to the pronghorn’s near-demise around
the turn of the century, modern, well managed hunting is
rarely a threat to any species of big-game animal in
America. In fact, it’s in large part the money raised
through the sale of hunting licenses and special taxes on
hunting-related gear that have made possible the successful
management programs that have brought pronghorn (and other
large ungulate species) back from the brink in recent
decades.

No, it’s not our hunting, but our real estate development
and agricultural endeavors–our houses and cities and
highways and parking lots and shopping malls and livestock
and fences and plowed fields and overgrazed rangelands and
sheer, unrestrained numbers–that threaten the future
of this wild creature and others.

So take advantage of the plentitude while you can. If
you’ve not seen pronghorns bounding with birdlike grace
across plain, prairie or desert, try to, soon. Your three
best bets are Teton and Yellow-stone national parks, both
in northwestern Wyoming, and the National Bison Range in
western Montana. The animals on these refuges, their
natural timidity buffered by long and proximate association
with unarmed humans, often will allow you to approach to
within Instamatic range–a real bonus for those
observers lacking SLR cameras and telephoto lenses but
wanting something more to take home than photos that
require you to explain, “See, Fred, it’s them little dots
a’way out there.

But go carefully when driving at night across those vast
Western ranges–“where the buffalo roam and the deer
and the antelope play”–else you might find your
vehicle wearing a pair of those unique pronghorn horns as a
hood ornament or, more disconcerting yet, wind up sharing
the driver’s seat with a prairie goat companion.