Classification Confusion: Though commonly referred to as an "antelope," the Pronghorn is not related to the antelope of Africa. The Pronghorn is a single species, the last surviving member of the prehistoric Antilocapridae family, and is found only on the Great Plains of North America. Unlike a true antelope that has permanent, unbranched horns, the Pronghorn has branched (pronged) horns with an outer sheath that is shed each year. At about 30 centimetres in length, the horns of the male (buck) are much longer than those of the female (doe).

At an average weight of 50 kilograms, the Pronghorn is somewhat smaller than the white-tail deer. It is tan in colour, with white bars across its throat and white markings on its rump, lower sides and underbelly. In addition to its powerful legs and well-developed respiratory system, the Pronghorn is equipped with 2 highly adaptive physical features that contribute to its survival:
• Erectile body hair - The Pronghorn can flare stiff, bristle-like hair patches on its rump to warn other Pronghorns about approaching danger.
• Keen eyesight - Large eyes, set high on the head and far back on the skull give the Pronghorn a wide-angle view of its grassland home, with vision equivalent to 8-power binoculars.

Curious Character: Despite its evolutionary advantages, the Pronghorn has one unusual trait that is well known to hunters. After fleeing from danger, the highly inquisitive animal will sometimes return to the scene of the alarm!

Under the province of Alberta's Antelope Management Plan, licensed antelope hunting, both by firearm and bow and arrow, is tied to seasonal populations. Hunting may be restricted by area, by method and by size, and licenses may be limited by a draw.

Haunting Hoodoos
Shaped like pedestals, pillars, and giant abstract sculptures, startling sandstone formations known as "hoodoos" rise several metres from the Upper Virgelle component of a geological region known as the Milk River Formation. Hoodoos, a common feature of badland topography, are soft rocks capped by more erosion-resistant rock remnants.

Over millions of years, layers of sand deposited by an ancient sea slowly compacted into sandstone of varying degrees of hardness. Many tiny layers produced harder rock, while larger layers resulted in softer stone. As wind and rain scoured the rock, sections of soft sandstone were washed away, but harder "caprocks" remained, preserving and protecting some of the material below, and resulting in oddly-shaped pinnacles and spires. Some Milk River hoodoos have window-like holes in their structures, formed when extra-hard ironstones fell away from softer, surrounding sandstone.

Hoodoos are remnants of slopes that are gradually being eroded away. The soft rock below the caprocks will eventually disappear, and the tops will tumble, fulfilling their geological destiny.

Raptors of the River
• Golden Eagle - Named for the buff-coloured feathers on the crown and nape of its neck, the Golden Eagle soars on thermal updrafts high above the Milk River valley, relying on its keen eyesight to spot mice, marmots, shrews, hares and Richardson's ground squirrels. Along with the Bald Eagle, the Golden Eagle is an uncommon, though not rare bird species of the Milk River region; unlike the Bald Eagle, it is a year-round resident, migrating only a short distance from its nesting grounds in search of food. Despite its name, the Golden Eagle is predominantly brown. It has a wide (2 metre) wingspan, and is the only species of eagle to have fully-feathered legs and feet. At a maximum weight of 6-7 kilograms, the Golden Eagle is larger than the Bald Eagle. Its usual nesting site is a ledge or cavity in the wall of the river's canyon, while its hunting grounds extend to nearby grasslands and cottonwood-lined coulees.
• Prairie Falcon - A more common summer resident of the Milk River valley, the hooked-beaked, brown-capped Prairie Falcon, identified by its white eye-patch and thin dark mustache, is about the size of a crow. Although smaller than its peregrine falcon relative, it is just as rapid in flight, slanting quickly down to prey on hares and ground squirrels. Cold-hardy and heat-tolerant, the Prairie Falcon is at home in dry open country, close to cliffs, canyons, coulees, badlands and rocky outcroppings. While Prairie Falcons may scrape a nest out of loose dirt in a cliff-side crevice, they commonly lay their 4-5 eggs in the former nest of another bird.
• Northern Harrier - This pale grey, white-rumped, owl-faced, long-winged, long-tailed hawk is commonly seen cruising low over open grasslands and along the riverbanks, occasionally stalling in mid-flight to pounce on mice, hares, frogs and smaller birds. Also known as Marsh Hawks, Northern Harriers inhabit most of North America, but are particularly numerous on the Great Plains.
• Other raptors found in the Milk River valley commonly include the Sharp-shinned Hawk, Swainson's Hawk, and American Kestrel, while less common species include the Bald Eagle, Cooper's Hawk, Red-tailed Hawk, and Ferruginous Hawk. Rare sightings of Turkey Vultures, Osprey, Northern Goshawks, Rough-legged Hawks and Merlins may be made.

Cottonwoods of the Coulees
Broad and shady in summer, golden yellow in autumn, the tall deciduous Cottonwoods of the Milk River valley burst with a snowy blizzard of silky white seeds ("fluorescences") in the spring, just as run-off levels reach their peaks.

Cottonwoods, native poplars of southern Alberta, rely on flood-like conditions to germinate their seeds in the fine-grained silt of the riverbank. Of the thousands of fluffy, cotton-like seeds discharged by the trees, few survive; those that succeed in landing on bare, moist soil drop roots immediately, racing to anchor their new growth before the soil dries out. Although established cottonwoods are hardy and long-lived (with a lifespan of up to 100 years), their reproduction is severely threatened by prolonged drought, damming, irrigation and other water diversions that alter regular flooding patterns.

Southern Alberta cottonwood species include the Western Plains Cottonwood, Narrowleafed Cottonwood and the Balsam Poplar (also known as Black Cottonwood). Cottonwoods growing in the coulees of the Milk River valley provide habitat for a wide variety of birds, mammals and reptiles, including White-tail deer and the Prairie rattlesnake.