While ponderosa pine is the most common tree species found in the forest, spruce can be found in the higher elevations. Elk, mule deer, pronghorn and white-tailed deer are commonly seen. Black bears have been spotted in the Black Hills. Cougars are increasing dramatically as a result of prolific herds of deer and elk. Coyotes, bighorn sheep and mountain goats are also frequently seen by visitors. Bald eagles, hawks, osprey, peregrine falcon and another two hundred species of birds can be found in this forest, especially along streams and near water sources.