distinct population: A population of animals or plants that has unique characteristics that differentiate it from other members of its species or subspecies.

ecosystem: An area that is studied for its interactions of species and the natural environment; it can be large or small.

endangered species: A species that is declining in number, possibly nearing the point of disappearing (extinction).

Endangered Species Act: A U.S. law enacted in 1973 that requires the federal government and individuals to take steps to protect endangered species.

extinction: Total disappearance of a species, subspecies, or distinct population.

fungi: Plants such as molds and mushrooms that have no chlorophyll.

habitat: The area in which a species lives.

keystone species: Species that have a disproportionately large effect on their community.

ornithologist: A scientist who studies birds.

slash-and-burn agriculture: Cutting down and then burning forests in order to make the land usable for farming.

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