The cougar is the largest felid in Oregon, and except for the jaguar, the largest felid in the western Hemisphere.

The skull of the cougar, also know as mountain lion, is massive; the canine teeth are large and slightly recurved. The heel pads of both fore and hind feet have three lobes on the posterior margin which are useful in separating the tracks of a cougar from those of other felids, such as the lynx. The dense and soft dorsal fur typically is tawny, but slate gray and reddish brown individuals are known. The venter is whitish. The back of the ears and tip of the very long tail are brownish black. The upper lip is white. Young cougars are light tan spotted with brownish black.

They are often active as much during the day as at night and use caves as retreats. They are largely solitary mammals; the only appreciable associations are of the female and its young and that of the female and male during mating season.

The cougar appears throughout western Oregon, but east of the Cascade Range the species is probably limited largely to the Ochoco, Blue and Wallowa mountains. They range over broad areas and move long distances. Although it is possible to observe cougars in almost any habitat type, they are usually found in remote forested areas and often in dense vegetation, especially in winter.

ODFW's Living with Wildlife, Cougar page has tips on living with cougars, recreating in cougar country, comparing cougar and dog tracks and more. 

Photo from ODFW