Common Name: Pronghorn
Species: Antilocapra americana
photo M. Noonan
Often called the prongbuck or
pronghorn antelope, the pronghorn is neither a deer nor
an antelope. Its scientific name, Antilocapra americana,
means “American antelope goat”, But this title is also a
misnomer, for pronghorn are not goats either. Pronghorn
are members of the Artiodactyla order of mammals. It
should be noted that pronghorn are classified in their
own separate family, Antilocapridae. Pronghorn’s special
taxonomic categorization is mainly due to their peculiar
horns. True horns are permanent, unbranched structures
consisting of a bony core surrounded by a durable
keratin sheath. A pronghorn’s keratin sheath, however,
is shed annually. Pronghorn are the only living species
that shed the outer coating of their horns in this way.
A few female pronghorn also have horns, but this is not
Pronghorn have tan bodies with
noticeable white markings on their neck, underside, and
rump. Males have black face marks, present beneath their
chin, atop their snout, and behind the ears. Large
protruding eyes provide pronghorn with a 360 field of
vision, and long, black eyelashes act as sun-visors.
Male and female pronghorn each have scent glands, which
are important for communication and courtship. Both
sexes have glands located between the toes and on the
rump, but males have ear and tail glands as well. Alarm
odors are produced by the rump glands, and ear glands of
males are used to mark territories. There are five
subspecies of pronghorn, slightly differing in color,
size and build. The northern forms (Oregon and American)
are located throughout the northwestern American
prairie, with desert scrubland forms located in the
southwestern American and Mexican deserts (Sonoran,
Mexican, and Peninsular).
Pronghorn roam the wide, open
ranges of the North American prairie and desert. Habitat
types include grasslands, brushlands, and desert
scrublands. Due to their extensive habitat type as well
as seasonal change, pronghorn eat a variety of flora.
Their teeth are adapted for this selective grazing,
growing continually. Their diet consists of cactus,
grass, browse, and forbs (herbs other than grass).
Shrubs are eaten all year round, with grasses used
primarily in the spring, and forbs, which are important
for healthy fawning, are eaten during the late fall.
Pronghorn also ingest several noxious weeds, making them
important for range management.
Pronghorn have adapted to the open
plains by developing extremely keen eyesight. Its large,
protruding eyes can detect movement up to 4 miles away.
This exceptional vision is used to spot approaching
predators and warning signals from other pronghorn over
long distances. When an immediate threat is present,
pronghorn escape with great speed. Reaching speeds of 60
miles per hour (mph), pronghorn are the fastest animals
in the western hemisphere. On the world scale, pronghorn
are only bested by the African cheetah, which are said
to attains sprints of 70mph. Pronghorn are very
'curious'. They will approach and inspect moving
objects, even predators, from long distances. This
'curiosity' was exploited by early settlers, whom
attracted pronghorn within gunshot range by waving cloth
rags attached to poles. This tactic, called 'flagging',
is now illegal.
The pronghorn’s breeding peak
occurs between mid-September and early October. Their
average gestation length is 252 days.
The size of the pronghorn
population prior to the European settlement of North
America was about 35 million. Their range extended from
eastern Washington and southern Manitoba, to Baja
California and northeastern Mexico. A 1920 count
estimated that fewer than 20,000 animals remained. A
population of 500,000 animals is currently estimated to
exist throughout the United States, Canada, and Mexico.
Our Experience with Pronghorn
A group of pronghorn was first
observed from our van, grazing in the vast expanse of
prairie along a backdrop of a vibrant, setting sun. We
quickly exited; glimpsing the pronghorn as they
gracefully took flight, by foot.
Estimated to once have numbered in
the millions, the pronghorn populations had fallen to
20,000 by the early 1900s. Since then, conservation
efforts have aided pronghorn in making an astounding
comeback, and the current population is estimated at
about 1 million individuals. This comeback is partly due
to a growing human awareness of pronghorn behavior.
Pronghorn do not jump fences but instead will choose to
crawl beneath them. Unfortunately many pronghorn became
entangled this way, often leading to injury or death. To
deal with the pronghorn’s difficulty in overcoming
fences, strategic placement of modified fence sections
is now common and this allows most pronghorn to pass
through prairie ranches. In many ways, this species can
be counted as a conservation success story. Wildlife
advocates, ranchers and government agencies all
cooperated in adapting human practices to allow this
wonderful species to co-exist with our activities in its
Artiodactyla – Mammalian Order,
meaning "even toed", which consists of all even-toed
hoofed mammals, including families that contain cattle,
antelope, deer, camels, and hippopotamuses
keratin – chief structural protein
of hair, nails, and horns