Top: I've never walked the Bench without having curious antelope shadow my movements. Being critters of great speed and possessing terrific eyesight, they're more comfortable when they are facing potential threats head-on. I've often watched the pronghorn follow coyotes or other predators as they passed through open meadows. Their actions sometimes take on the aspect of being a game, as they first dog a hunting coyote, and then are chased in turn by the the frustrated hunter. While it looks like play, the 'game' is in deadly earnest, with both players seeking to control the outcome. This particular pronghorn followed Paul and I for about a mile across the wide Bench, then disappeared over the rise.
The pronghorn, or Antilocapra americana, is a true American native. Its Latin name means the "American goat-antelope", but it is neither goat nor antelope, though it is often referred to as an antelope. The pronghorn is the sole surviving member of a family that dates back at least 20 million years. It is the only animal in the world that has branching horns. The horns are shed annually like the antlers of deer, moose, and elk. It is the only animal in the world to shed its horns. Both sexes have horns, but the female has only tiny spikes that are rarely pronged like the males. The outer sheath falls off each fall, but grows back by the following summer. It has a gall bladder like sheep or goats, and lacks dewclaws as does the giraffe. Second in speed only to the cheetah of Africa, the pronghorn can reach speeds of 60 mph. I've driven by running pronghorn in the Shirley Basin region of Wyoming that matched the speed of my car easily as I accelerated past 55 mph. The cheetah though, can only hold its higher speed for a short distance, while the pronghorn can maintain a fast pace for hours if necessary. Being superbly adapted to existing in a dry environment, it can get all of its moisture requirements from the plants that it eats. The small pronghorn can survive a 180 degree range of temperatures, from 130 in the deserts to 50 below zero in the higher elevations where it also thrives.
Fall signals the beginning of the intensive mating season. The territorial bucks are especially aggressive in defending their areas. Brief fights develop between males and occasionally one is seriously injured. Ambitious bucks may develop harems of 3 to 8 or more does.
The young are born in late May or early June with about 60% of the births being twins. At birth, fawns weigh 5 to 6 pounds and lack the spots that are characteristic of deer and elk fawns. The newborn do not have an odor and instinctively lie motionless for hours. This is their main defense from predators such as bobcats, eagles, and coyotes. Paul and I watched as a group of pronghorn sprinted across Shirley Basin, with the young racing right along with them. As though on a signal, all of the young suddenly dropped to the ground and remained motionless while the adults continued on for a short distance. Without using binoculars, it was nearly impossible to see the young pronghorn.

Below: Aspen crowd the edge of a dry lake bed on the west end of the Bench. In wet years, there is often a wide pond here for a month or two each spring.