From the tiny town of Plush, Hart Mountain Rd crosses the Warner Lakes Basin, climbs into the spectacular, near-vertical Hart Mountain fault block (peak elevation over 8000ft) and emerges onto the prairie-like expanses of the Hart Mountain National Antelope Refuge. Roughly 3700 pronghorn antelope are protected within the refuge's 435 sq miles – a shadow of the millions of pronghorns that once roamed North America, but at least the population has remained steady.
Pronghorns are not true antelopes, and have horns rather than antlers, shedding only the outer hairy sheath and growing a new covering each year. Pronghorns are the world's second-fastest land animal (after the cheetah), having been clocked at 60mph. For the best odds of seeing them, try Lookout Point on Blue Sky Road.
The refuge also protects bighorn sheep, reintroduced to Hart Mountain in the 1950s and now living on the steep western side of the refuge. Cougar, bobcat, coyote, mule deer and a wide variety of birds (including sage grouse) are also among the 300-plus species of wildlife that inhabit the area. During sage grouse mating season, March to June, a special permit is required for some areas; the chest-puffing birds put on quite an entertaining show.
Hart Mountain has an extensive network of 4WD trails and single-tracks through isolated areas, making for good hiking and mountain biking. Spot ancient rock carvings along the loop trail around Petroglyph Lake, or hike along Skyline Drive (open in summer; 4WD vehicles only), where you have a decent chance at spotting antelope or sage grouse.
At the often unstaffed refuge headquarters you can pick up brochures any time and use the area's only potable water and toilet facilities. Pitch a tent at the free Hot Springs Campground, about 4 miles south of HQ. There's a lovely wooded creek plus an open-air bathhouse that traps a hot spring – just the thing after a dusty day of exploring. There's an undeveloped hot-spring pool nearby.
If you're just passing through, allow two to three hours to travel the 75 miles between Plush and Frenchglen (about 50 miles is on a slow gravel surface); make sure you have plenty of gas, food and water. None of the refuge's roads are paved; call in winter or after heavy rains to check that they are passable.