Invasive Species


Early Detection Surveys
One way to stop the damage an invasive species may inflict on an ecosystem is to control or eliminate the species when its populations are still small. However, scientists cannot detect every single patch of an invasive species - they simply don't have the time or resources. Students and other volunteers can help scientists by conducting early detection surveys.

An early detection survey locates problem species that are in the process of invading an area. For example, an early detection survey could be used to determine whether purple loosestrife is present in a wetland. While it is important to eventually determine the size of invasive species patches in an ecosystem, early detection surveys are only conducted to determine if a species is present or absent.

Early Detection Survey Technique
Using the method described below, you will be able to determine if the invasive species in which you are interested has invaded a specific study area.



  1. Learn about invasive species of concern in your area, particularly those that are just beginning to invade. You may find information on one of the websites listed on our links page. Another option is to contact an organization concerned about your local environment and/or invasive species (for example, a land trust, your local town conservation commission, state parks, university departments, the Nature Conservancy). These organizations will likely be able to provide you with information about local invasive species, and may even ask you to conduct a survey on their land.
  2. Decide upon which species you will look for, and which area should be the focus of your survey (for example, a state park, a nature preserve, or your school's property).
  3. Learn how to identify the species for which you will be searching. The library, local environmental organization, or websites may have useful identification guides. Be sure that your species is easily recognized during the time of year in which you will be searching for it.
  4. Decide on a survey method. Because invasive species often first invade travel corridors (for example, roads and hiking trails), you may want to focus your search along these areas. Consider in what types of habitats your invasive species grows. Mark the sites to be surveyed on your map.
  5. Walk through your site and record information about your invasive species. For example, you may want to walk all of the trails in a nature preserve. Record what you noticed, including information on whether the species was present and if so, in what quantities.
  6. Before you move to the next site, clean off your shoes and remove any plant parts that may be attached to your clothes. This will help prevent invasive species from spreading to new sites.
  7. Record on your map where the invasive species was found. If you are working with a local organization, be sure to report your findings to them.


Based on the data you have recorded on your map and in your field notebook, is the species you surveyed coming into your study area? What type of sites is it colonizing? Are its populations large or small? Do your results agree with your predictions? For example, if you expected to find a species, was it present?

If you (or your friend or classmate) conducted a similar study on a different study site, compare your results. Was the same invasive species present in both sites? Was the species present in similar amounts (size of patches, density, etc)? Why do you think this is the case?

For more information on how to analyze or report your results, consult Invasion Ecology.


Copyright 2009 Environmental Inquiry, Cornell University and Penn State University