Invasive species
Brown tree snake was introduced into Guam in 1952. Native birds had never experienced predation by snakes, and 8 species have been eradicated by this alien predator.	Purple loosestrife was imported to the U.S. in the 1800s from Eurasia. It has invaded wetlands with aggressive growth that overwhelms native plants, replacing diverse communities with monocultures of loosestrife.	Zebra mussels invaded the U.S. from Eurasia in the 1980s in the ballast water of cargo ships. They feed on small plankton, removing food for fish in the Great Lakes. They also clog intake pipes of water-treatment plants and factories.