U.S. Department of State
U.S. Department of State
Other State Department Archive SitesU.S. Department of State
U.S. Department of State
U.S. Department of State
U.S. Department of State
U.S. Department of State
U.S. Department of State
U.S. Department of State
Home Issues & Press Travel & Business Countries Youth & Education Careers About State Video
 You are in: Under Secretary for Democracy and Global Affairs > Oceans and International Environmental and Scientific Affairs > Oceans > Invasive Species > Case Studies

Case Study: Brown Tree Snake

brown tree snakeThe brown tree snake Boiga irregularis provides a startling example of the negative effects invasive species can have on indigenous fauna. The brown tree snake, which is native to Papua New Guinea, was accidentally introduced to Guam in the 1940s through U.S. military transports after World War II. Aggressive and venomous, the brown tree snake has no natural predators on Guam and soon established itself throughout the entire island. It has now reached densities of up to 30,000 per square mile.

The brown tree snake feeds on rats, shrews, and lizards, but prefers birds. The indigenous birds of Guam evolved in a snake-free habitat and consequently lack the protective behavior or barriers of other birds, making them easy prey for the brown tree snake. Preying on eggs and birds alike, the snake has eliminated 9 of the 11 native land bird species in Guam and many of the non-native species. Its predation of native birds has been so complete that the brown tree snake is now sustained almost entirely by feeding on the introduced lizard species of the island.

The brown tree snake has taken its toll on the human population, as well. Approximately 200 people have been treated for snakebites, as the snake often enters houses through air ducts or sewage lines. The brown tree snake also crawls along electrical lines, causing approximately one power outage every four days, which results in a cost of over $1 million annually. The brown tree snake is able to live for long periods of time without food, allowing the snake to survive in cargo holds of ships or planes. Brown tree snakes have been intercepted six times at the Honolulu airport but the island has been spared colonization as of yet. If one pregnant snake escaped into the brush, however, it could damage the natural fauna of Hawaii as well as its tourist industry. For this reason, the United States has become engaged in the struggle to control and eradicate the brown tree snake.

In 1992, the Department of Defense was granted $1 million in new money for brown tree snake research and control. The 1990 Nonindigenous Aquatic Nuisance Prevention and Control Act directed that a program be developed to control the snake in Guam. Controls for the brown tree snake include fumigation of cargo with methyl bromide as well as the use of toxicants, baits, and traps. Dog teams are being used currently in Honolulu for snake detection. The costs of brown tree snake detection and control are estimated at $2.5 million per year.

- 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). p. 247-248

- Corn, M.L., J. Rowson, E.H. Buck, E. Fischer, "CRS Issue Brief for Congress- Harmful Non-Native Species:

Issues for Congress RL30123," (Washington, DC: Congressional Research Service, April 8, 1999)

Related Link:
-- Midcontinent Ecological Science Center


  Back to top

U.S. Department of State
USA.govU.S. Department of StateUpdates  |   Frequent Questions  |   Contact Us  |   Email this Page  |   Subject Index  |   Search
The Office of Electronic Information, Bureau of Public Affairs, manages this site as a portal for information from the U.S. State Department. External links to other Internet sites should not be construed as an endorsement of the views or privacy policies contained therein.
About state.gov  |   Privacy Notice  |   FOIA  |   Copyright Information  |   Other U.S. Government Information

Published by the U.S. Department of State Website at http://www.state.gov maintained by the Bureau of Public Affairs.