Pronghorn Antelope

Antilocapra americana

Description

Pronghorns have barrel-shaped bodies, standing from 86-88cm at the shoulder. Depending on the age and sex, pronghorns tend to weigh between 35-70kg. The dense fur of this animal has a layer of “guard hair”, coarse fur which each hair is hollow and filled with air to provide insulation. Guard hairs are able to be erected or relaxed to provide heat regulation; more air that can be trapped between the fur and the skin will provide more insulation. A finer, shorter layer of fur lies below the guard hair. Pronghorn have rufous brown fur with cream-colored underbellies, rumps, and neck patches. The fur of southern populations of pronghorn tends to be paler in color than northern populations. Males of this species have short, black mane, neck patch, and stripe on the forehead. Female pronghorn have small patch of black hair around the nose. The rump of a pronghorn has white, erectile fur. This species has black horns (keratinized sheaths growing over a bony extension of the frontal bone or “cancellous bone”) that stand erect. Each horn has a posterior hook and short anterior prong, the anterior prong is unique to this species. The horns of a pronghorn begin to grow at six months of age; males reach their maximum horn size in 2-3 years. Both sexes of this species have horns but the horns of females tend to be smaller (never taller than ear length).

Habitat

This animal can be found in Canada’s southern Prairie Provinces and the plains, basins, and deserts of western United States and Mexico. Their habitat ranges from sea level to 3500m. Pronghorns live in grasslands, sage scrublands/chaparral and deserts.

Feeding Behavior and Diet

Pronghorn are herbivores that feed on sage, forbs, and grasses. They use foregut fermentation with rumination to break down the cellulose of plants. This species will also occasionally consume cacti in some places. In sage scrublands they are dependent on sage brush as their main food source, especially in winter. They will dig through snow with their hooves to find vegetation or travel to wind-blown ridges where the vegetation is not covered by snow. The speed and endurance of this species allows it to forage over great distances. Pronghorn do not need to drink free-standing water; their water consumption varies depending on the water content of the plants consumed.

Reproduction

Northern populations of pronghorn breed between mid-September to October while southern populations breed from July to October. This species is polygynous, males will defend territories containing a small harem of females (does) from March until early October. Scent glands located on either side of the jaw, neck, between the hooves, rump, and above the tail are used as communication signals and also for mate selection. Two hundred fifty two days after mating, the female gives birth to one or two fawns. All females give birth within a few days of each other, this is known as synchronous birth. Young begin to consume vegetation by 3 weeks old. Female pronghorn reach sexual maturity at 5 months old but do not typically breed until they are 16 months old. Males reach sexual maturity by their first year but do not typically breed until their third year because they are outcompeted by older males for females.

Months and Times of Activity

Seasonal movements vary regionally. In winter months pronghorns form wintering herds that may move 160 km and then disperse in the spring until they form smaller herds in the summer. Males typically claim territories from late March to October.

Special Features, Stories, Relationships

•    Pronghorns have incredible speed and endurance. They are known as the fastest New World mammal and can travel 98 km/h when sprinting. Within just days of birth they are able to outrun a human. They have very large lungs for their body size and are able to consume more oxygen. This allows pronghorns to produce ATP aerobically, unlike the cheetah which uses anaerobic respiration while running at high speeds.
•    Fence-lines make pronghorns very nervous because they cannot jump. There is not enough suspension in their legs to allow them to jump because of muscular and joint adaptations which allow them to run at high speeds over long periods of time.
•    To read Native American legends featuring this animal go to: http://www.aaanativearts.com/mailbag-archive/1603-what-is-the-cultural-significance-of-pronghorns-to-native-americans.html#axzz3Gn1bGKZe
•    Children’s book featuring this animal: Pronghorn by Natalie Lunis

References

Krejci, K. and T. Dewey 2009. "Antilocapra americana" (On-line), Animal Diversity Web. Accessed November 04, 2014 at http://animaldiversity.ummz.umich.edu/accounts/Antilocapra_americana/