Often, the terms “invasive” and “non-native” are used interchangeably, when in fact they do not necessarily describe the same thing. A non-native species is anything that has been introduced (either intentionally or not) outside of its normal range. Invasive species are non-native species that often display particular characteristics like fast growth, large numbers of offspring, and rapid maturation. These qualities, and a lack of the natural predators and diseases that help control them in their native environment, allow invasive species to rapidly grow and spread, overwhelming and displacing natives. The critical natural refuges provided by San Francisco Bay Area national parks are threatened by a number of invasive plant and animal species. Please see the links on this page to learn more.