Most of us have a general idea of what an endangered, threatened, or extinct species is, but biologists have certain definitions for each. In general, an endangered species is one that’s in immediate danger of becoming extinct. Its numbers are unusually low, and it needs protection in order to survive. The peregrine falcon, the whooping crane, the green pitcher plant, and thousands of other plants and animals throughout the world are endangered.

Threatened species are those species whose populations aren’t yet low enough to be in immediate danger of extinction. They face serious problems, though, and are likely to become endangered if the problems affecting them don’t let up.

Extinct species are no longer living. The Stegosaurus, the dodo, and the passenger pigeon are examples of extinct species.

Another term you may have heard is extirpated. Extirpated is when a species is locally extinct. For example, Indiana use to be home to elk, mountain lions and black bears. Although each of these species still exist, they no longer exist in the wild in Indiana.