U.S. Fish & Wildlife Service

Invasive Species


Learn More About Invasive Species

Frequently Asked Question About Invasive Species

General Questions

What Can I Do?

Aquatic Nuisance Species

FWS Questions on Invasives

Miscellaneous Questions

Q: What are invasive species (also defines the terms “exotic” and “native”)?

A: To understand what an invasive species is, one must first understand the difference between an exotic species and a native species. An exotic species is any species, including its seeds, eggs, spores, or other biological material capable of propagating that species, that is not native to that habitat. Other terms sometimes used for exotic species include “non-native.” “non-indigenous,” and “alien.” A native species is a species that, other than as a result of an introduction, historically occurs/occurred in that particular habitat. These definitions come from Executive Order 13112.

An invasive species is an exotic species whose introduction into an ecosystem in which the species is not native causes or is likely to cause environmental or economic harm or harm to human health. It is important to note that when we talk about a species being invasive, we are talking about ecosystem or environmental boundaries, not political ones. In addition to the many invasive species from outside the U.S., there are many species from within the U.S. that are invasive in other parts of the country because they are not native to the ecosystem in which they have become established.

Q: Why are invasive species a problem?

A: The introduction of invasive species can have a dramatic effect on our natural resources, human health, and economy. When non-native species are introduced into an ecosystem in which they did not evolve their populations sometimes explode in numbers. The reason for this is that in a natural or native community, species evolve together into an ecosystem with many checks and balances that limit the population growth of any one species. These checks and balances include such things as: predators, herbivores, diseases, parasites, other organisms competing for the same resources and limiting environmental factors. These checks and balances form the complex web of life that makes up an ecosystem and in which a native species competes for survival. However, when an organism is introduced into an ecosystem in which it did not evolve naturally, it no longer has those limits and its numbers can sometimes dramatically increase. The unnaturally large population numbers can then have severe impacts. The following discussion highlights examples of each of these impacts.

Impacts to Natural Resources and the Environment

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 in that ecosystem because they are suddenly competing with a new species for the same resources (food, water, shelter, etc.). The invasive species can 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 such as diseases and natural disasters. Invasive species can:

  • Reduce the ability of streams to make historic water deliveries. Examples include:
    • Phragmites colonization of river channels in Nebraska, which has resulted in localized flooding and a reduced capacity for safe water conveyance downstream.
    • Tamarisk (saltcedar) spreading along stream channels, bars, and beaches throughout the arid interior West, which has altered riverine and riparian habitats, caused localized flooding, and increased the loss of already-scarce streamflow to evapotranspiration.
  • Displace native plant communities and/or radically change the nature of the habitats they invade. Examples include:
    • Purple loosestrife, water hyacinth, yellow star thistle, and many other invasive plants across the nation
    • Zebra mussels in our rivers and streams
    • Nutria in our nation’s coastal marshes.
  • Compete for the same natural resources and life requirements (food, water, space, shelter) as native species and degrade local ecologies by disrupting the food chain. Examples include:
    • The ruffe and round goby in the Great Lakes
    • The brown tree snake in Guam
    • The introduction of rats and the Indian mongoose to Hawaii
  • Cause the extinction of native species. Examples include:
    • The brown tree snake in Guam has caused the extirpation of many of Guam’s native terrestrial vertebrates, including fruit bats, lizards, and virtually all of the island’s forest birds.
    • Goats caused the extinction of 8 plants on San Clemente Island in California.
  • Increase soil erosion and fire hazard.
    • One example includes cheatgrass, which was partly responsible for the fires at Hanford Reach National Monument and Saddle Mountain National Wildlife Refuge.
  • Decrease the quality of understory habitat in forests and facilitate the spread of other invasive species.
    • One example includes wild pigs in the Hawaiian forests.
  • Decrease the quality and amount of range for wildlife (and range animals).
    • Examples include leafy spurge and yellow starthistle which are problems in the northwestern states, where rangeland with more than 10-20% leafy spurge will not be grazed by cattle thus also affect the quality of range for wildlife.
  • Degrade aquatic habitats and clog waterways. Examples include:
    • Giant salvinia, in the south, can quickly cover an entire water body. This prevents sunlight from getting to the aquatic plant and phytoplankton and preventing new oxygen from entering the waters. Decaying organic material then uses up the existing oxygen thus causing harm to organisms that need oxygen. The salvinia also prevents many forms of aquatic recreation such as fishing and boating.
    • Other plants that cause similar problems across the nation include alligatorweed, Brazilian elodea, water hyacinth, hydrilla, Eurasian water-milfoil, water lettuce, and Caulerpa taxifolia (an invasive seaweed which was eradicated from San Diego, CA waters).

Invasive Species Impacts to the Economy

In addition to harming the natural world, invasive species also have serious effects on our economy. Invasive species can alter the habitats they invade to the point that natural-resource based businesses can suffer. We also spend millions of dollars every year on the eradication of invasive species and the restoration of the habitats they have invaded. Invasive species can:

  • Cause reduced revenues to natural resource based businesses.
    • Giant salvinia completely covers water bodies making it impossible to go fishing and allowing no space for waterfowl to land thus making hunting much less profitable. Aquaculture and rice production could also be severely impacted by giant salvinia.
    • The sea lamprey and round goby have caused decreases in native fish populations in the Great Lakes.
    • The Indian mongoose damages some papaya and banana crops in Hawaii
    • Honeybee mites can kill bees, thus damaging honey crops
  • Affect boaters and fisherman by changing fish habitat and clogging waterways.
    • Hydrilla and water hyacinth are clogging waterways in the south. Giant salvinia may soon join in if it cannot be contained.
  • Act as hosts for other damaging organisms.
    • Buckthorn is an invasive shrub that also carries an oat rust that damages oat crops.
    • Johnsongrass, an invasive grass native to the Mediterranean, harbors viruses that affect corn.
  • Decrease the quality and quantity of rangeland.
    • Leafy spurge and yellow starthistle are problems in the northwestern states. Rangeland with more than 10-20% leafy spurge will not be grazed by cattle.
  • Decrease land values and cost the landowner time and money.
    • Many perennial weeds (knapweed, leafy spurge) are known to reduce production and thus ultimately reduce land values.
  • Cause soil erosion.
    • This is common when native plants with fibrous roots are replaced with invasive broad-leaved plants with taproots.
  • Cause damage and increased maintenance costs to power plants and industrial water systems.
    • Zebra mussels, quagga mussels, and Asian clams.
    • Aquatic nuisance plants like giant salvinia and water hyacinth.
  • Have a negative impact of tourism.
    • In Colorado, many invasive plants are replacing the beautiful blend of grasses and wildflowers in our refuges and parks that visitors come to photograph.
    • In Hawaii, the tourism and real estate industries are being affected by a combination of invasive species. The disturbingly loud call of a Puerto Rican frog known as the coqui is keeping tourists awake at night, while invasive seaweeds are damaging coral reef ecosystems and washing up on the beaches in huge amounts, causing foul odors as they decay.
    • In the Sonoran Desert, which attracts a lot of eco-tourists due to the desert’s high plant diversity, dense bufflegrass stands can cause the disappearance of 90 out of 100 species (see Invasive Plants of the Sonoran Desert).

Invasive Species Impacts to Human Health

Although most of the impacts caused by invasive species are to our ecology and economy, invasive species can also have severe impacts on human health. Invasive species can:

  • Serve as vectors (carriers) for human diseases
    • The Asian tiger mosquito can carry the West Nile virus.
    • The Indian Mongoose can carry rabies.
    • At least one species of invasive snail carries schistosomiasis.
    • Cholera has been found in the ballast water of ships.
  • Be poisonous or caustic to humans.
    • Approximately half of the poisonous plants in the eastern U.S. in non-agricultural areas are non-native and many are invasive
    • The Brazilian pepper tree in Florida produces allergens that cause respiratory difficulty and contact dermatitis.
    • African honey bees and fire ants can bite or sting.

Q: How do invasive species get to the United States?

A: There are many different pathways through which invasive species are intentionally and unintentionally introduced into the United States. In the early colonial days, before we were aware of the concept of invasive species, colonists brought many of their favorite plants and animals with them to the new world. Many of these species, although useful, have become problems over the years, or were carriers of other species (diseases, insects, seeds, etc) that were invasive.

  • Examples include: horses, cows, Queen Anne’s lace, domestic pigs in New England, dandelions, and common mullein.

Some species are (or have been in the past) deliberately brought into the United States for specific reasons (such as biocontrol or for use as pets) and are either released into the wild on purpose or escape where they then unexpectedly become an invasive species problem. These are called intentional introductions. One of the newest pathways for intentional introductions is mail order shopping through the Internet.

  • Examples include: the gypsy moth, nutria (a muskrat-like rodent), exotic plants via the nursery trade such as kudzu and multi-flora rose, plants from the seed trade such as crabgrass and johnsongrass, escapes from aquaculture facilities, and the mongoose in Hawaii. Examples of unwanted pets that get released into the wild include aquatic organisms dumped from unwanted aquariums and snakes and lizards that get too large for their owners to take care of.

Many species arrive here accidentally, without our knowledge. These are called unintentional introductions. Pathways for unintentional introductions include species arriving in foreign ballast water, hidden in wood packing material, hidden in other vegetation via the nursery trade, hidden aboard ships, hitchhiking on other species, and many other pathways.

  • Examples include: the Asian long-horned beetle, chestnut blight, zebra mussel, European green crab, and the coqui (a Puerto Rican frog)

Q: What parts of the U.S. have invasive species?

A: Every region of the United States has invasive species problems. However, in some regions the problem is much more severe than others. Some of the places with the most invasive species problems include Hawaii, Florida, the Great Lakes, and the west coast. These places have larger numbers of invasive species because they are transportation hubs (marine, air, tourism) or because they have tropical climates that are more favorable for survival of the invasive species. But those are not the only places that have invasive species problems. Invasive species can be found from Alaska to Louisiana and from Maine to Texas. They can be found in our forests, fields and wetlands, and in our streams, rivers and bays, and even off our coastlines.

Q: Are all exotic (non-native) species considered invasive?

A: No, not all exotic species are invasive. In many cases, a species not native to an area is not adapted to it. If you introduced African elephants to Alaska - they would not survive. In other cases, however, a new species can do well in a new habitat, such as striped bass introduced to the Sacramento River in California. Only in a few cases do introduced species "go wild" and grow invasively, beyond acceptable levels. Current research seems to indicate that approximately 4-19% of the non-native species introduced into the U.S. might be invasive (U.S. Congress, Office of Technology Assessment, 1993).

Q: Are all exotic species harmful?

A: No, not all exotic species are considered harmful. Non-native plants are fundamental to our lifestyle - most of our food crops, such as potatoes and wheat, are not native to the United States. Invasive species, however, are exotic organisms that have gone beyond being useful and have become harmful. A species is not usually recognized as invasive until it causes some sort of harm or cost to the ecology, economy, or to human health. Attempts to plant kudzu as a forage crop and an ornamental plant and attempts to develop a nutria population for fur harvest, for example, both backfired and have now become invasive species problems. There are some benefits to all species - but invasive species do more harm than good.

Q: How many invasive species are there in the U.S?

A: Although the numbers vary widely, some of the current research estimates that there are approximately 50,000 (Pimentel, 2004) non-native species in the United States today. However, of that 50,000 species, approximately 4,300 have been considered invasive species (Corn et. al, 1999).

Q: How can we know if an exotic species has the potential to be invasive?

A: Although there is not one specific trait or a specific set of traits common to all invasive species, there is a suite of traits that invasive species often have. Not all invasive species will have all of these traits, but most invasive species seem to have one or more of these traits. The traits include (Williams and Meffe, 1998):

  • High rate of reproduction
  • Pioneer Species (able to colonize areas after they have been disturbed)
  • Short generation times
  • Long-lived
  • High dispersal rates
  • Single-parent reproduction
  • Vegetative or clonal reproduction
  • High genetic variability
  • Broad native range / Tolerant of wide range of conditions / Habitat generalist (can live in many different types of habitats)
  • Abundant in native range
  • Broad diet
  • Gregarious
  • Human commensal (lives in close association with humans)

Q: How are invasive species eradicated, controlled and/or managed?

A: When an invasive species first becomes introduced into a new area, there may be a chance to eradicate it through a rapid response action if it is detected in time. If eradication is not possible, then the species may be subject to control and management efforts. Regardless of whether the goal is eradication or control/management, there are a suite of different options, which differ depending on the species, which one must consider. When making decisions on which options to use, one must use an Integrated Pest Management approach to choose the options which will be the most environmentally sound yet still affect the invasive species as strongly as possible. The various options for eradication/control/management include:

Physical or Mechanical Control - This type of control involves physically removing the invasive species (i.e. harvesting) or using barriers or traps to prevent their spread or to capture them. For invasive plants, mowing is another example of physical control.

Chemical Control - This type of control involves all sorts of pesticides (herbicides, insecticides, fungicides, piscicides, etc.) Although chemical use can be very effective, they can be very dangerous to other species or to the ecosystem in general and must be used in an environmentally sound manner. The key is to choose chemicals that are low-risk yet effective and that can be applied when the pest is at its most vulnerable.

Cultural Management - Cultural management is the manipulation of the habitat in ways that increase the mortality of the invasive species or reduce its rates of increase and damage. Cultural management that can affect invasive species including: selection of pest resistant varieties of crops, mulching, winter cover crops, changing planting dates to minimize insect impact, burning, flooding, crop rotations that include non-susceptible crops, moisture management, addition of beneficial insect habitat, or other habitat alterations that help the native species compete better against the invasive ones.

Biological Controls - This type of control is the purposeful use of an invasive species’ enemies (predators, parasites, and pathogens) – in other words other exotic species – to reduce the invasive species populations. This option involves much research and testing to be sure the species to be used preys only on the target invasive species.

What Can I Do?

Q: What can I do about invasive species?

A: There is a lot that the private citizen can do to help in our fight against invasive species. Two of the most important things you can do to prevent the introduction and spread of invasive species is to clean your outdoor recreation gear and to not release unwanted pets or dump the contents of an unwanted aquarium into the wild.

  • Visit the Habitattitude Web Site for more information on how the pet and aquarium owner can prevent the spread of invasive species.
  • Aquatic recreationsists should always clean and drain their boats and gear before leaving a site. Aquatic invasive plants can get stuck on various parts of a boat, and aquatic organisms can be transported in water. For a comprehensive list of how one can help prevent the spread of aquatic nuisance species, please visit the Stop Aquatic Hitchhikers/Protect Your Waters Web Site.
  • The seeds of invasive plants can easily get transported in mud and dirt. Always remember to clean the dirt off of your hiking boots or off of your vehicle before you leave an area.

Visit the What You Can Do section of our web portal for a more comprehensive list of what you can do to help prevent the spread of invasive species.

Q: How can I determine if a plant or animal that I have seen or caught is invasive?

A: If you have a species that you think might be invasive, there are a number of options available to you. You could:

  • Consult local natural resource guidebooks and field guides.
  • Consult web pages on the Internet that can help one identify invasive species
    • The Plants Database provides information about the plants of the U.S. and its territories and can help you determine if a plant is not native to your area.
    • NatureServe Explorer is an authoritative online source for information on more than 65,000 plants, animals, and ecosystems of the United States and Canada. Explorer includes particularly in-depth coverage for rare and endangered species, but can also help one determine whether a species is native to a particular region.
    • The Invasive Species Information Node has links to many identification resources.
  • Try and locate some help at your local park, nature center, nursery, university, aquarium, or zoo.
  • Contact your State Department of Natural Resources office or your local U.S. Fish and Wildlife Service Office.
  • Contact your local Cooperative Extension System office. These offices, part of the Cooperative State Research, Education, and Extension Service, provide answers to commonly encountered problems on topics such as: agriculture, animal and plant health, nutrition, and environmental issues.
  • Contact USDA for assistance in the identification of plant, insect, snail or slug, roundworms, and plant pathogens.

Q: What can I do if I have invasive species on my property?

A: If you find invasive species on your property, it is up to you to decide what to do. You can leave them alone, or you might want to try and eradicate or control them. This may or may not be possible depending on the extent of the problem and whether your neighbors all around you have the species on their land as well. If you have a significant amount of property infested with invasives and would like to find out whether invasive species can be eradicated or habitats on your property can be restored, all of the sources in the question above may be of help. In addition, there are many Service programs and other government programs that could be of assistance. To find out more about these programs, please visit the Grants page of the Invasive Species Web Portal’s Partnerships Page.

Q: Where can I go to report an invasive species on public land?

A: If you are in a National or State Park, National Wildlife Refuge, or other piece of public land and you think you may have discovered a new invasive species, you should contact the closest park or refuge office and see if they are aware of the invasive species.

If you think you have found an aquatic invasive species, you should try and alert the local office as mentioned above, but there are two other ways you can report the discovery.

  • To report an aquatic invasive species by phone, the U.S. Fish and Wildlife Service and the U.S. Geological Survey maintain an ANS Hotline at 800-STOP-ANS (877-786-7267).
  • To report an aquatic invasive species online, please follow this link to the USGS Nonindigenous Aquatic Species Sighting Report Form.

Q: Where can I get a list of the Federal or State noxious weeds?

A: USDA’s Animal and Plant Health Inspection Service maintains lists of Federal and State noxious weeds.

Q: Where can I get a list of the species that are invasive for my State?

A: To get a list of the species that are considered invasive in your area, contact your State Department of Natural Resources.

Q: I’m looking for alternatives to invasive plants to plant in my yard. Where can I find lists of native plants suitable for my area?

A: Most states have native plant societies that might be able to provide lists of native plants suitable for your area. There are also many texts on native plants that can be found in your local library or book or garden store.

Visit the What You Can Do section of this web portal to see a larger list of resources one can consult for native plant alternatives, including some excellent resources on the internet.

Q: Where can I learn more about the subject of invasive species?

A: There are many excellent sources for additional information on exotic species. If you are doing research on invasive species for a school project, the first place you should investigate is the resources of your local or University library as they are often good sources for information. In addition to this web site, there are the web sites of other government agencies (see question 26), the links from our News and Resources page, and also some general references below.

One of the best places to start learning about invasive species is through the Frequently Asked Questions (FAQ’s) of various invasive species web pages. In addition to this set of FAQ’s, there are many others that are quite informative. Here are the links to several good sets of FAQ’s:

There are also numerous excellent publications available for download on the Internet:

There are also many books and publications that can be purchased on the subject of invasive species:

  • Bright, Chris. 1998. Life Out of Bounds. Worldwatch Institute. W.W. Norton and Company, New York, NY.
  • Devine, Robert, S. 1998. Alien Invasion: America’s Battle with Non-Native Animals and Plants. National Geographic Society.
  • Cox, George, W. 1999. Alien Species in North America and Hawaii. Island Press.
  • Mooney, H.A. and R. J. Hobbs. 2000. Invasive Species in a Changing World. Island Press.
  • Simberloff, et. al. 1997. Strangers in Paradise: Impact and Management of Non-Indigenous Species in Florida. Island Press.
  • Williamson, M. 1996. Biological Invasions. Chapman and Hall.

Q: How can I receive informational alerts about invasive species in my State or Region?

A: If you are interested in receiving notifications regarding aquatic invasive species, then consider signing up for the USGS Nonindigenous Aquatic Species Alert System. The NAS Alert System tracks the spread of invasive species nationwide. Users can report nonindigenous and invasive aquatic species they sight, automatically receive email alerts, or perform searches on aquatic species. The system is flexible, providing two different perspectives - one to a user interested in an area, the other to users interested in a species - whether the user chooses automatic alerts or prefers to search the site.

Q: How can I find information on a particular species?

A: Information on specific species and their life histories can be found on many web sites all across the Internet and can be easily found with a Google search. One can usually find a lot of information just by searching by the scientific or common name of the species. However, the following links go directly to web sites with multiple species profiles or fact sheets.

Aquatic Nuisance Species

Q: What are Aquatic Nuisance Species?

A: Aquatic nuisance species are invasive plants and animals that occur in our country’s aquatic habitats including lakes, streams, rivers, estuaries, wetlands of all types and marine environments. These species threaten the diversity or abundance of native species, the ecological stability of infested waters, and the commercial, agricultural, aquacultural or recreational activities dependent on such waters. These species are the focus of the ANSTF. The term “aquatic nuisance species” is synonymous with “aquatic invasive species.”

Q: What is the Non-Indigenous Aquatic Nuisance Species Prevention and Control Act?

A: In 1990, Congress passed landmark legislation, the Nonindigenous Aquatic Nuisance Prevention and Control Act of 1990, (as amended Through P.L. 106–580, Dec. 29, 2000) to facilitate an effective governmental response to zebra mussel impacts on manufacturing and power generating processes in the Great Lakes’ states. A key provision of this law was the creation of the national Aquatic Nuisance Species (ANS) Task Force. Six years later with the continued expansion of the aquatic invasive species (AIS) issue and their mounting impacts, Congress reauthorized the law and expanded its scope beyond ballast water introductions and zebra mussel control and management. It called on the ANS Task Force to work with its state and local government partners to address these challenges, take action, and produce tangible results.

Q: What is the Aquatic Nuisance Species Task Force? How does it relate to the Non-Indigenous Aquatic Nuisance Species Prevention and Control Act?

A: The Aquatic Nuisance Species Task Force is an intergovernmental organization, administered by the Fish and Wildlife Service, committed to preventing and controlling aquatic nuisance species and implementing the Nonindigenous Aquatic Nuisance Prevention and Control Act (NANPCA). Although the Act was passed in response to zebra mussels, the Act focuses on all aquatics, including aquatic plants.

The ANSTF, co-chaired by Fish and Wildlife Service and the National Oceanic and Atmospheric Administration, is comprised of both Federal agencies and ex-officio members representing affected entities. The Task Force coordinates Federal governmental efforts dealing with aquatic nuisance species with those of state and local governments, non-governmental organizations, academic institutions, and the private sector. The Fish and Wildlife Service recognizes that battling invasive species is not something that can be done by one agency or organization. Federal, state, local and tribal governments, as well as non-governmental organizations, academic institutions, and the public, must work together to get ahead of new infestations like giant salvinia before they reach uncontrollable levels.

Q: Why do aquatic nuisance species and aquatic habitats deserve special attention?
A: Aquatic nuisance species deserve special attention because our nations’ waters are already severely degraded. Consider these statistics:
  • 92 to 98 percent of the linear miles of rivers and stream are so altered that they do not fit criteria for National Wild and Scenic Rivers or United States Geologic Survey Benchmark Streams.
  • An estimated 80% of natural riparian vegetation has been lost.
  • Only 42 Rivers across the United States still flow unimpeded by dams.
  • Twenty-two States have lost 50% of their original wetlands. Ten States have lost 70% or more.
  • Approximately ten thousand non-indigenous aquatic species are currently present in U.S. waters, many of them with severe ecological consequences.

The result of this degradation is that between 33 and 75 percent of aquatic species are rare or extinct. More specifically, the Nature Conservancy’s 1997 Species Report Card found that:

  • 37% of the nation’s freshwater fish fauna are at risk of extinction.
  • 51% percent of U.S. crayfish species are in jeopardy.
  • At least 67% of the nation’s freshwater mussels are at risk of extinction, and almost 1 in 10 may already have vanished forever.
  • 40% of our nation’s amphibians are imperiled or vulnerable.
  • At least 106 major populations of salmon and steelhead trout on the west Coast have been extirpated, and an additional 214 salmon, steelhead trout, and sea-run cutthroat trout stocks are at risk of extinction.

With our nation’s aquatic habitats already in dire need of attention, it is important that we do our best to prevent further degradation from the introduction of new aquatic nuisance species.

FWS Questions on Invasives

Q: Why does the Fish and Wildlife Service care about invasive species?

A: The U.S. Fish and Wildlife Service is the only agency of the U.S. Government whose primary responsibility is the conservation of fish, wildlife, and plants. Because of our responsibilities, the Service is very concerned about the impacts that invasive species are having across the Nation. Invasive plants and animals have many impacts on fish and wildlife resources. Invasive species degrade, change or displace native habitats and compete with our native wildlife for food, water, shelter and space, and are thus harmful to our fish, wildlife and plant resources.

Q: What is the Service doing about Invasive Species?

A: The U.S. Fish and Wildlife Service addresses invasive species issues through a variety of programs and partnerships. The Service’s Invasive Species efforts take proactive approaches to address intentional and unintentional introductions, combat the spread of existing invaders on and off Service lands, and maintain the Service as a leader in invasive species prevention and control. [Note: the text below is the same text as from the FWS Invasive Programs Page]

  • The Branch of Invasive Species, part of the Service's Fisheries Program office in Washington D.C., leads the Service’s Aquatic Nuisance Species (ANS) Program. The Branch’s Invasive Species web site has links to information on its ANS Program, the ANS Task Force, the Stop Aquatic Hitchhikers and Habitattitude public awareness campaigns, and the 100th Meridian Initiative.
  • The Branch of Invasive Species also conducts activities related to the listing of organisms as Injurious Wildlife.
  • The Service’s National Wildlife Refuge System addresses invasive species issues on its 545 Refuges, encompassing approximately 96 million acres of wildlife habitat.
  • Several Service programs are involved in the Habitat Restoration of degraded wildlife habitats included those impacted by invasive species.
  • The Endangered Species Program is involved in the recovery of listed (threatened and endangered) species and the ecosystems on which they depend. Invasive species are often part of the reason these species are threatened.
  • The Division of Environmental Quality addresses invasive species issues through its work on Integrated Pest Management, its work to promote the use of native plants as part of its efforts to protect Pollinators, and its work on biocontrol.
  • The Service’s Office of Law Enforcement, using wildlife inspectors at 32 major U.S. airports, ocean ports, and border crossings, seeks to prevent the introduction of injurious wildlife through its wildlife inspection program.

For more details on Service programs that address invasive species, or to learn more about invasive species subjects (prevention, contronl, education, etc.) please visit the FWS Invasive Programs section of this web site.

Q: What are Injurious Wildlife?

A: Injurious Wildlife, is the term given to wild mammals, wild birds, fish, mollusks, crustaceans, amphibians, and reptiles, that have been determined to be injurious to the health and welfare of humans, the interests of agriculture, horticulture or forestry, and the welfare and survival of wildlife resources of the U.S. Under the Lacey Act, the Secretary of the Interior is authorized to regulate the importation and transport of injurious wildlife species, including the organism’s offspring and eggs.

Miscellaneous Questions

Q: Is FWS the only part of the Federal Government that cares about invasive species?

A: No, the invasive species issue is much too big for any one program to address on its own. There are many other government programs that have invasive species programs. The most comprehensive list of Federal government web sites pertaining to invasive species can be found at the National Invasive Species Information Center in the Agencies and Organizations section of their Resource Library.

Q: What is E.O. 13112 (Executive Order 13112)?

A: On February 3, 1999, Executive Order 13112 was signed, which directed Federal agencies to address invasive species issues to not authorize, fund, or carry out actions likely to cause or promote the introduction or spread of invasive species, and also established the National Invasive Species Council. Follow this link to view Executive Order 13112.

Q: Where can I go for other fish and wildlife related questions that do not involve invasive species?

A: For answers to general questions about the Fish and Wildlife Service and other questions commonly asked, please refer to the Fish and Wildlife Service’s General FAQ’s

For answers to questions on Endangered Species and related topics, please refer to the U.S. Fish and Wildlife Service’s Endangered Species Web Page.

If you think you have habitat on your own property that is restorable and would like more information on how we could help, please visit the Partners for Fish and Wildlife Web Page.


Corn, L.C., E.H. Buck, J. Rawson, and E. Fischer. 1999. Harmful Non-Native Species: Issues for Congress. Congressional Research Service Issue Brief, RL30123.

Pimentel, D., R. Zuniga, and D. Morrison. 2004. Update on the environmental and economic costs associated with alien-invasive species in the United States. Ecological Economics Volume 52, Issue 3, 15 February 2005, Pages 273-288

U.S. Congress, Office of Technology Assessment, Harmful Non-Indigenous Species in the United States, OTA-F-565 (Washington, DC: U.S. Government Printing Office, September 1993).

Williams, J.D. and G.K.Meffe. 1998. Nonindigenous species. In: Mac, M.J. P.A. Opler, C.E. Puckett Haecker, and P.D. Doran. 1998. Status and trends of the nation’s biological resources, Vol.1. U.S. Department of the Interior, U.S. Geological Survey, Reston, VA.