On May 14, 2007 in Washington DC, the USPS issued a stamp that featured a stylized drawing of a bighorn sheep (Ovis Canadensis). This kind of sheep is found from southwestern Canada to northern Mexico; its range includes the colder, higher elevations of the Rocky Mountains and some of the hottest, most arid regions of the American Southwest and Mexico. Sure-footed and swift climbers, bighorn sheep zigzag up and down cliff faces with ease. They are highly gregarious animals, sometimes forming groups of more than 50 animals. To create the image on the stamp, artist Nancy Stahl worked from photographs of bighorn sheep. Sure-footed and swift climbers, bighorn sheep zigzag up and down cliff faces with ease. They are highly gregarious animals, sometimes forming groups of more than 50 animals. To create the image on the stamp, artist Nancy Stahl worked from photographs of bighorn sheep.