Big Animals/Small Animals

Whenever I read a fantasy novel with very large animals (generally dragons, but there are similar issues with stuff like giants as well) and/or animals in dungeons or hidden deeply in caves, I start thinking about stuff like this.

To see why, you only have to look at the tiger’s relatives in the Americas. A male mountain lion weighs in at about 150 pounds — about a quarter the size of a large tiger. To keep itself fed, a mountain lion prowls an area ranging from around 50 to as much as 400 square miles. The American bobcat is a considerably smaller animal. At 25 pounds, it’s about one-sixth the size of the mountain lion, and it makes do with about one-sixth the area. In the eastern United States, there are no mountain lions left (barring the few who may have been turned out by exotic pet owners having second thoughts). Bobcats in the eastern United States number in the hundreds of thousands.

Well, my contemplations are usually not quite about territorial size, but more about energy balances. In particular, how much food such an animal or population (a bunch of elves or dwarves, for instance) would require.