An invasive species is an introduced, nonnative organism (disease, parasite, plant, or animal) that begins to spread or expand its range from the site of its original introduction and that has the potential to cause harm to the environment, the economy, or to human health.
A few well-known examples include the unintentional introduction of the West Nile virus, chestnut blight, the South American fire ant, zebra mussels, Burmese pythons, and sea lamprey. These are in addition to the intentional introductions of salt cedar (Tamarisk), kudzu vine, house sparrows, starlings, and nutria.
Harmful, non-native species can be found in all ecosystems across the United States. These species can cause costly economic and ecological damage each year including crop decimation, clogging of water facilities and waterways, wildlife and human disease transmission, threats to fisheries, increased fire vulnerability, and adverse effects for ranchers and farmers.
Learn more: USGS Invasive Species Program
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- FAQ
Are invasive snakes dangerous?
Free-ranging snakes representing dozens of species from around the world are discovered in the United States in any given year, usually as a result of escapees or releases from the pet trade, but most of these don't appear to have established a reproductive population. Any animal can be problematic when released in places where it is not native. For example, the brown tree snake was introduced to...
Are there invasive reptiles other than Burmese pythons in the United States that people should be concerned about?
Free-ranging, non-native reptiles representing dozens of species from around the world escape or are illegally released in the United States every year. Many of these species fail to establish reproductive populations, but some are successful. Florida is a major transportation hub and has a climate that’s suitable for many invasive species, so the state has the world’s largest number of...
How have invasive pythons impacted Florida ecosystems?
Non-native Burmese pythons have established a breeding population in South Florida and are one of the most concerning invasive species in Everglades National Park. Pythons compete with native wildlife for food, which includes mammals, birds, and other reptiles. Severe mammal declines in Everglades National Park have been linked to Burmese pythons.The most severe declines in native species have...
What are the potential effects of snakeheads to our waters?
During all of their life stages, snakehead fish compete with native species for food and habitat. A major concern is that snakeheads might out-compete (and eventually displace) important native or other established predatory fish that share the same habitat. As adults, snakeheads can be voracious predators. Should snakeheads become established in North American ecosystems, their predatory behavior...
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