Unlike the thickly forested regions east of the Mississippi, the arid Great Plains were largely devoid of trees and other vegetation save for a matting of short grasses. Even so, the Plains teemed with wildlife. The jackrabbit and prairie dog required a minimum of water. Other species, like the deer, antelope, coyote and wolf, flourished in the parched conditions and also possessed the speed and elusiveness necessary to survival in such open country. Those traits were not shared by the most famous of the Plains animals, the buffalo or American bison. Their nearsightedness and ponderous movements made them easy prey to hunters, but until the latter portion of the 19th century, buffalo roamed the Plains in immense herds, their numbers estimated in the tens of millions. Beyond the western rim of the Plains, the high forests and grassy valleys between mountain peaks sheltered a great variety of wildlife — grizzly and brown bear, elk, mountain lion, bighorn sheep — while in the streams and lake margins, beaver and other fur-bearing species were plentiful.