The Pronghorn - An example of a monotypic genera

One of a kind

The pronghorn is an endangered animal which is endemic to the USA. It is also one which belongs to monotypic genera, meaning it is the only remaining member of a particular genus.

There are a number of species which belong to monotypic genera. Some of these are the red panda, the black rhinoceros, the moose and the numbat. These rather unique animals are mostly endangered although some are coping well.

In some cases, others of the genus have become extinct over the centuries. These 'sole representatives' are very important simply because they are the last of a line in the evolutionary world.

Pronghorns, also known as prong buck and pronghorn antelope, belong to the order Artiodactyla. These are the even-toed ungulates (hoofed animals). The weight is borne almost evenly on the third and fourth toes. Their scientific 'family' is Antilocapridea. There were once at least 12 antilocaprid representatives but Antilocapra americana is now the only species still living. It closely resembles the true antelopes. The subspecies include the Sonoran pronghorn found in Arizona and Mexico, the Mexican pronghorn, Oregon pronghorn and the Baja California pronghorn (A.a.peninsularis). The last is regarded as critically endangered.

Pronghorn(66808)Credit: Wikimedia

The fleet-footed pronghorn is among the speediest animals in North America. They are also extremely tough. Speeds of 53 mph (86kph) may be reached and, at half that speed, they can travel for miles at a time without tiring. Although not faster than the cheetah, they can sustain high speeds longer than can cheetahs.

The range of the pronghorn extends from southern Saskatchewan and Alberta through south-west Minnesota and Texas west to coastal California and through to northern Mexico. Some groups have an overland migration route that covers over 160 miles from the Pioneer Mountains foothills to the Continental Divide.

Pronghorns are mostly found in grassland areas but also in brushland and desert regions.

Both sexes have horns. The slender horns are laterally flattened blades of bone. These grow from the frontal bones of the head. The covering of skin develops into a sheath of keratin which sheds and regrows each year. The horns curve backwards then divide into two forward-facing points or 'prongs'. The horns may be 30cms or more long.

PronghornCredit: Wikimedia

The males have well-developed horns but the horns of the female may be absent, malformed or small. Females have straight horns, very rarely pronged. The eye sockets are high on the skull and quite prominent. The eyes themselves are large with a 320 degree field of vision.

Pronghorns are about a metre tall at the shoulder and 1.3 to 1.5 metres long. Males weigh between 36 and 70kg. They are reddish brown in colour and the hair follicles are hollow. The stomach is white and there are wide, white stripes on the throat. When startled, the hair on the rump raises to reveal a white patch. The feet have two hooves with no dewclaws. Males also have a small patch of black hair at the angle of the lower jaw.

The lungs and heart of the pronghorn are very large. It is built for speed and can easily surpass the speed of any of its present natural predators. It is likely that its predators once include the American cheetah which would account for the need of such speed. The pronghorn, however, is not a good jumper.

Pronghorns eat a number of plants that are unpalatable or toxic to domestic livestock. Pronghorns are ruminants, that is they swallow food then regurgitate it later to chew it more thoroughly. It is a herbivore and lives on herbs, grass, sagebrush and other vegetation. Interestingly, pronghorns have a gall bladder which deer do not.

Social behaviour
Mixed sex herds form during the winter. By early spring, bachelor groups have congregated as have groups of females. Adult males become solitary. Females form a dominance hierarchy. Males either defend a territory which females can enter or they may defend a group or 'harem' of females. In areas of high rainfall, adult males seem to be more territorial and will scent-mark their areas. They may change their mating strategies depending on conditions.

Females may visit several males, switching between prospective partners. They may incite fights between the males. If a fight should occur, females mate immediately with the winning male.

Pronghorns breed in mid-September and have a gestation period of 235 days. New-borns weigh between 2 and 4 kg and are able to outrun a man within a few days. One or two fawns are born to each doe. For the first 3 to 4 weeks, fawns are hidden in vegetation. Later fawns join 'nurseries', only spending short periods each day with their mothers. By 15 to 16 months, the pronghorn is sexually mature though it is rare for males to breed before the age of 3. The lifespan is ten years or perhaps a little longer.

Wolves, coyotes, bobcats and cougars prey on the pronghorn but they have to catch them first! Anecdotal evidence suggests that golden eagles prey on fawns. Stress is put on the pronghorn by fencing of its ranges for sheep and agriculture. In some places, their natural habitat is being protected and bans placed on hunting. Migration corridors have been threatened by fragmentation and blocking of traditional routes. Local populations have been affected by blue tongue disease spread by sheep in the area.

The pronghorn is an attractive animal and its survival seems more certain than it was a few decades ago.