American lions are not a very common sight in the United States, but if you've ever seen one of these felines, you know that they can make for an impressive first impression. The American lion is also known as the cougar. These large lions are North and South American lions. They live in the Rocky Mountains and are native to North America. There are a few differences between these cats and the British Lion, though: the cougar is a solitary animal. Unlike other species, the mountain lilies keep to themselves, and will fight to defend their territory. Females will move to a new den site every few weeks, and males will do the same to protect their kittens..