What is an invasive species and why are they a problem?
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.
More than 6,500 of these harmful, non-native species cause more than 100 billion dollars in damage each year to the U.S. economy. Costly effects include 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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Scroll down to hear and download calls of Cuban treefrogs and two native treefrogs.
USGS Tracks How Hurricane Floodwaters Spread Non-Native Freshwater Plants and Animals
Hurricanes Harvey, Irma, Maria, and Nate may have spread non-native freshwater plants and animals into new water bodies, where some of them can disrupt living communities or change the landscape.
Wildfire and Invasive Species Drives Increasing Size and Cost of Public Land Restoration Efforts
An examination of long-term data for lands managed by the Bureau of Land Management finds that land treatments in the southwestern United States are increasingly large, expensive and related to fire and invasive species control.
Invasive Pest May Not Be Only Cause of Recent Louisiana Marsh Die-off
A non-native insect infestation may not be the only factor involved in the ongoing die-back of a marsh grass in the Mississippi River’s “bird foot delta,” the ecologically and economically important part of coastal Louisiana where the river meets the Gulf of Mexico.
A Breakthrough in Controlling Invasive Fish
On a windy July morning on Lake Superior’s Whitefish Bay, fisherman Ralph Wilcox of the Sault Ste. Marie Tribe of Chippewa Indians and his son, Dan, netted 300 pounds of wriggling whitefish. The mild-flavored salmon relative is served in restaurants, in smoked fish spreads, and as gefilte fish at Passover. However, two of the fish in the Michigan fishermen’s nets were badly wounded.
Around 600 Non-Native Mountain Goats Now Roam the Olympic Mountains
Population has Increased 8 Percent a Year Since 2004
USGS Study Reveals Interactive Effects of Climate Change, Invasive Species on Native Fish
A new USGS study shows non-native Brown Trout can place a burden on native Brook Trout under the increased water temperatures climate change can cause.
Controlling Those Suckers Known as Sea Lamprey
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In Hot Water: Climate Change is Affecting North American Fish
Climate change is already affecting inland fish across North America -- including some fish that are popular with anglers. Scientists are seeing a variety of changes in how inland fish reproduce, grow and where they can live.
Continued Decline of the Northern Spotted Owl Associated with the Invasive Barred Owl, Habitat Loss, and Climate Variation
CORVALLIS, Ore. – Northern spotted owl populations are declining in all parts of their range in the Pacific Northwest, according to research published in The Condor. Based on data from 11 study areas across Washington, Oregon and northern California, a rangewide decline of nearly 4 percent per year was estimated from 1985 to 2013.
Invasive Northern Snakehead Carries Bacteria as Bad as its Bite
The invasive northern snakehead fish found in the mid-Atlantic area is now cause for more concern, potentially bringing diseases into the region that may spread to native fish and wildlife, according to a team of U.S. Geological Survey scientists.
Invasive Annual Grass Fills the Space Between Shrubs, Mojave
An unburned low elevation community in the central Mojave where the interspaces between shrubs have been filled in with a continuous layer of Mediterranean split grass Schismus barbatus. If a fire started here it would spread much more rapidly and be far more extensive than in a low elevation community where the interspaces are rocky or bare.
Invasive Burmese Python
Invasive Burmese python in the Greater Everglades Photograph credit: Brian Smith, USGS
Axis deer bounds through a grassy field
Snakehead Fish
Snakehead fish are originally from China and Korea, but recently they've been found in Maryland, Virginia, Arkansas, California, and Florida.
What's the Big Idea?— Turning to eDNA to Detect Invasive Species
Adam Sepulveda, research zoologist at the USGS Northern Rocky Mountain Science Center, explains a scientists at NOROCK are using environmental DNA — the identification of species through biological information they leave behind in their habitat — to detect invasive species and how this method could change the way scientists find evidence of biodiversity in ecosystems.
Sample of invasive northern pike in south central Alaska
USGS scientist Adam Sepulveda sits with a sample of invasive northern pike in south central Alaska.
An invasive American bullfrog with tracking device.
An invasive American bullfrog with tracking device.
Invasive New Zealand mud snails as seen under a microscope.
Invasive New Zealand mud snails as seen under a microscope.
Sea Lamprey, an Invasive Fish
Invasive sea lamprey prey on commercially important fish species such as lake trout, living off of the blood and body fluids of adult fish. It is one of many fish species that USGS scientists study from the USGS Research Vessel Muskie. These lamprey belong to the Great Lakes Fisheries Commission.
The R/V Muskie was temporarily moored in Buffalo, N.Y., August 8 and 9
...Invasive tamarisk on the Colorado River.
This image is of invasive tamarisk (salt cedar) growing on the banks of the Colorado River.