The term 'CARLSBAD CAVERNS DWELLER' refers to a BAT, which is a three-letter word. Bats are mammals of the order Chiroptera, and they are the only mammals capable of true flight. They are found in almost every part of the world, and they inhabit a variety of habitats, including caves. The Carlsbad Caverns in New Mexico are home to a large population of bats, making them an ideal habitat for these creatures.