An invasive species is one that is not native to an ecosystem and which causes, or is likely to cause, economic or environmental harm or harm to human health. Invasive species are harmful to our natural resources (fish, wildlife, plants and overall ecosystem health) because they disrupt natural communities and ecological processes. This causes harm to the native species because they are forced to compete with a new species for the same resources (food, water, shelter, etc.). The invasive species typically outcompete the native species for food and habitats and sometimes even cause their extinction. Even if the native species are not completely eliminated, the ecosystem often becomes much less diverse. A less diverse ecosystem is more susceptible to further disturbances from diseases and natural disasters.
Learn how the refuge controls invasive species.