Animal Moments

And the Antelope Play

The pronghorn (Antilocapra americana) is a familiar and delightful sight on the prairies and
grasslands of
northern Colorado, and throughout Wyoming. Known commonly as the "antelope,"
the pronghorn is actually the single extant member of its own family, the Antilocapridae
("goat-antelopes"), but it is neither a goat nor an antelope.

The animal is named for the male's horns: they are black, with backward-pointing hooks and
forward-pointing prongs. Females also have horns, which are smaller and usually lack the
prongs. The horn has a permanent bony core surrounded by a sheath that is shed annually.
This is a unique type of deciduous horn.

 

The pronghorn has a striking coloration: the coat is dark reddish tan above and white below.
The males have a black mask and black patches on the sides of the neck.
Females are in general smaller than males.

 

The pronghorn eats a wide variety of vegetation, only partly consisting of grasses.
They favor the forbs (low-growing leafy plants), and they can eat and digest plants that are
noxious to many other grazing animals. They are often seen grazing in fields of alfafa,
their brown and white bodies contrasting beautifully with the deep green.

 

It is estimated that some 40 million pronghorn ranged across western North America and
northern Mexico in the mid 1800s. They were a popular game animal, in part because of
their tendency to stop and stare at an oncoming predator. The practice of "flagging," in
which a concealed hunter simply waved a stick or pole on which a handerchief was tied,
would catch the attention of the pronghorn and make the animal an easier target.

 

By the 1920s there were fewer than 13,000 pronghorn remaining. Energetic conservation
efforts succeeded in increasing their numbers to about 450,000 at present. The pronghorn
is still listed as an endangered animal, since the Mexican herds remain sparse.

The pronghorn's curiosity makes it easy to view and photograph. If you stop along the road
and stand with your vehicle behind you, the pronghorn will run away for a bit, but then will stop,
turn, and stare in your direction. If you stay still, the animals will return to their cautious browsing.
But if you step away from your vehicle so the pronghorn can see your human silhouette, they
will run away again.

And they are fast! In fact, the pronghorn is very nearly the fastest mammal on the planet.
Pronghorn have been clocked at some 55 miles per hour. They can easily outrun any predator
that shares their habitat. The question arises, why did the pronghorn develop such speed?
The answer may be that the only faster animal living today, the cheetah (
Acinonyx jubatus),
which now inhabits sub-Saharan Africa and northern Iran, actually evolved in North America.

Cheetahs have been clocked at 70 miles per hour. They had to be that fast, if they were going
to have pronghorn for dinner.

The photo above shows a small herd of pronghorn we watched at Lake DeSmet in northern Wyoming.
The animals have just turned and started to graze again after running when we stepped out of our car.
You can easily see the pronged horns on the bucks at the extreme left and in the upper middle of the
picture. There is also a buck in the middle of the herd whose black markings on face and neck are
very visible.

The picture below shows the herd in a wider shot. (Look to the lower left corner.) Lake DeSmet is behind
us, and before us are the foothills and higher elevations of the Big Horn Mountains.

Oh, give me a home!