invasive species

An invasive species is a living thing that moves into a new region. Species often become "invasive" as a result of human activities. Invasive species can threaten local plants and animals by competing with them for resources. Sometimes this can lead to the extinction of native species. Once invasive species become established, they can greatly change a habitat.

Image credits: European starling, courtesy of Dr. W. Dan Sudia, FLMNH Photo Gallery of Southeastern U.S. Birds African land snail, courtesy of Duane Meier, Honolulu Zoo, Wicked Willy photo gallery cat, courtesy of AMNH.