Threats to survival:

Threats to survival of the Sonoran pronghorn and the Peninsular pronghorn: poaching; habitat loss due to livestock overgrazing and restriction of movement due to fences. Natural predators of pronghorn fawns include coyotes, bobcats, and golden eagles, but these predators aren't usually able to kill healthy adult pronghorn.

Special Features

• Pronghorn are the sole living member of the family Antilocapridae, "an ancient family dating back 20 million years" (EDF).
• There are 5 living subspecies of pronghorn:
• Antilocapra americana americana - the American pronghorn, found throughout the Great Plains
• Antilocapra americana oregona - the Oregon pronghorn, found in a small area near the border of Oregon, Idaho, California, and Nevada.
• Antilocapra americana sonoriensis - the Sonoran pronghorn, found in southern Arizona and the Sonora province of northern Mexico
• Antilocapra americana mexicana - the Mexican pronghorn - found in the Mexican provinces of Chihuahua and Coahuila
• Antilocapra americana peninsularis - the Peninsular pronghorn, also called the Baja California pronghorn, found in Baja California, Mexico
• Male pronghorn are called bucks; females, does; and young pronghorn, fawns.
• Pronghorn rely primarily on their keen eyesight to warn them of danger. They also have acute senses of hearing and smell. 
• Oddly enough, according to several sources, wild pronghorn do not have a tendency to leap fences like deer. Pronghorn crawl under them instead.
  
  

  Physical characteristics

  Male pronghorn grow horns 12-18 inches long. The horn consists of two parts: a bony core and a black outer sheath made of keratin. Unlike most animals, for which horns are permanent structures, pronghorn shed their horn sheaths each year following the breeding season. The horn sheaths grow back by the next year's breeding season. Females sometimes grow horns 3-4 inches in length. Male pronghorn also have black patches on their cheeks.

  Pronghorn are well adapted to both the heat of summer and the extreme winter temperatures that occur throughout portions of their range. Their coat consists of an outer layer of hollow, air-filled hairs that provide insulation from the cold. In the summer, the animal molts to a thinner coat. Pronghorn are also able to erect their body hair to allow for the release of body heat.

  Pronghorn also have a short "mane" about 2 - 4 inches long.

  They have large eyes in relation to their body size. Their eyes protrude from the side of the head giving them a wide angle of vision. They have acute eyesight and can detect movement 4 miles away. Their vision has been compared to that of a human looking through high-power binoculars.

  Male pronghorn have 9 scent glands: 2 over the rump, 4 between the toes, 2 beneath the ears, and 1 above the tail. Females have just 6, and lack those below the ears and above the tail. Scent from the glands is used to mark territories and during mating rituals. The rump glands produce alarm odors that supplement the warning "flash" produced by the white rump hairs. Some references claim that the alarm odors can even be detected by humans (Geist 284, Fowler 996).

  Pronghorn are able to raise their long, white rump hairs to signal approaching danger. This creates a "flash" of white visible from a long distance.

  Just how fast is a pronghorn?

  Pronghorn are the fastest land mammals in the Western hemisphere. They are capable of bursts of speed in excess of 60 mph. Their only competitor for the title of the world's fastest land mammal is the cheetah, which some claim is capable of speeds up to 70 mph. However, some scientists dispute the top speed of the cheetah and thus, the pronghorn may be the fastest. Pronghorn are considered by many to be the world's fastest land animal over long distances as they can easily sustain speeds of 35-40 miles per hour over long distances.

  Part of what makes these animals so quick is their physical anatomy – they clearly are built for speed. They have a high-capacity trachea (windpipe) and lungs. They run with their mouth open, not due to exhaustion, but to take in extra oxygen. When moving at high speeds, pronghorn cover the ground in 14 to 25 foot bounds.

Social Structure & Behavior

Pronghorn group size and structure varies with the changing seasons.

Late fall to winter: Loose aggregations of mixed sexes and ages form at the end of the breeding season. Groups of 100 or more animals may gather during winter.

Spring to summer: "During the spring and summer the herd breaks up into smaller groups segre gated by sex." Does and fawns gather in groups, usually with 12 or fewer members. Young males form small bachelor groups. Males 3 years and older compete for and defend territories. (University of Michigan) Older, more dominant males scent-mark and defend territories during the breeding season, and try to collect harems of females.

Communication-vocalizations and visual signals in addition to the one ones previously described (U. of Mich.): "Calves bleat when separated from their mother. Mother grunt when seeking their calves. Males "roar "during fights. Males and females blow through their nostrils when angered." Breeding & Care of Young:

Sexual maturity occurs at 15-17 months of age. While does often mate at this age, bucks generally do not mate until they are older and have established dominance, usually at 3 years of age.

The breeding season, or rut, in the wild occurs over a 2-3 week period during September or October. Breeding may begin in August in southern portions of the pronghorn's range.

Prong horn have an interesting reproductive strategy. Females ovulate 4-7 eggs at mating time. Usually 4 fertilized eggs then implant in the uterus. However, not all the embryos will survive to term, as some embryos are killed when punctured by projections that grow from the embryos destined to survive. Thus, a female pronghorn typically gives birth to two offspring at a time. First-time mothers may give birth to just one fawn. Gestation=250 days In the wild births usually occur in May or June.

Fawns typically weigh 5-9 pounds at birth and lack the spots typical of deer and elk fawns. Pronghorn fawn coats are more gray in color than the hair color of adults.

At two days of age a pronghorn fawn can outrun a human. At four days it can beat an average horse.

Fawns after begin feeding on vegetation at 3 weeks of age, but aren't weaned until 4-5 months.