Species Profiles

Species Profiles --> Brown Tree Snake

Scientific name: Boiga irregularis

Common name: Brown tree snake

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Taxonomic Information: Boiga irregularis [Integrated Taxonomic Information System (ITIS)]

Identification: Distinguishing characteristics for the brown tree snake include: a vertical pupil; rear fangs; a large head in relation to the body; and  brownish or greenish coloring, with cross-band markings. About 18” at hatching; grows to about 3’ in first year. Adults can grow to 8’ and weigh up to 5 lbs. Mildly venomous to humans; while not fatal, its bite can nevertheless cause severe sickness in young children.

Photos:

Figure 1:  USGS

Figure 2:  USGS

Life Cycle: Feeds upon a wide variety of birds, lizards, small mammals, bird and reptile eggs, and small common household pets. Reproduces beginning around age 3; deposits up to 12 eggs once or twice a year in caves, hollow trees, and other areas protected from drying and overheating.  The eggs are then abandoned, and hatch about 90 days later.

• An Overview of the Biology of the Brown Tree Snake, a Costly Introduced Pet on Pacific Islands [USDA/USGS]

Habitat: Tropical. Lives mostly in trees and shrubs, where it forages at night. Frequently invades holes and buildings in urban habitats in search of food and hiding spots. Seeks refuge from heat and bright sunlight in daytime.

Distribution: Native to Solomon Islands; New Guinea; northern and eastern Australia; eastern Indonesia. Invasive to Guam. Sighted, but not known to be established in Hawaii; Texas; Saipan; Tinian; Rota; Wake Oahu; Kwajalein; Pohnpei; Okinawa; Diego Garcia.

• Summary of Documented Arrivals of BTS to Islands & the Continental U.S. [USGS-Patuxent Wildlife Research Center]

Abundance: Up to 13,000 snakes per square mile on Guam.

Optimal Growth/Spread Conditions:

Introduction: Guam: Believed to have been introduced via cargo transported by U.S. military ships during World War II.

Dispersion Techniques: Secretive and nocturnal, the brown tree snake can coil itself in small, highly confined hiding spaces. Dispersed mainly by stowing away in cargo on planes and ships, and within plane wheel-wells.

Known Predators or Biological Controls: Predators include pigs and monitor lizards.

Other Controls: Methyl bromide (testing stage); calcium cyanide (testing stage); traps; bait.

• Control and Containment of the Brown Tree Snake [USGS-Midcontinent Ecological Research Center]
• Candidate Repellants, Oral & Dermal Toxicants, & Fumigants for Brown Tree Snake Control [USDA]
• Feasibility of Controlling Brown Tree Snake in Small Plots [USDA/USGS]
• Trapping Strategies for Deterring the Spread of Brown Tree Snakes from Guam [USDA]
• Managing Island Biotas: Brown Tree Snake Control Using Barrier Technology [USGS/USDA]
• Effectiveness of the Detector Dogs Used for Deterring the Dispersal of Brown Tree Snakes [USDA]

Environmental Impacts: Has virtually wiped out the native forest birds of Guam, including the flightless rail. Twelve species of bird unique to the island have disappeared as a direct result of brown tree snake predation.

• Impacts and Damages from Brown Tree Snakes [USGS-Fort Collins Science Center]

Economic Impacts: Since 1978, more than 1200 power outages on Guam have been caused by the brown tree snake, which frequently scales power lines and transformers. The outages and damage to equipment represent a significant economic burden to the island.

• Economic Damages from the Brown Tree Snake [USGS-Fort Collins Science Center]

Legislation:

• U.S. Code: Title 16, Section 4728: Brown Tree Snake Control Program [Cornell University]

Current Research Links:

• Control & Containment of the Brown Tree Snake [USGS/Fort Collins Science Center]
• Brown Tree Snake [USDA/APHIS-Wildlife Services]

Other Links:

• The Brown Tree Snake on Guam, 2001 [Thomas H. Fritts and Dawn Leasman-Tanner [U.S. Geological Survey, Fort Collins Science Center]
• USGS Helps Protect Island Life & Biodiversity: Snake Invaders Threaten Island Ecosystem [USGS]
• Brown Tree Snake Bibliography [UGSG-Fort Collins Science Center]
• No Escape from Guam: Stopping the Spread of the Brown Tree Snake [USDA]
• Brown Tree Snake [Commonwealth of Northern Mariana Islands]
• APHIS News Alert on Brown Tree Snake [USDA]
• Changeable feasts: how the brown treesnake and other aliens changed Guam's food webs; Interactive versions of Fritts & Rodda's food web diagrams [University of Guam]
• The Brown Tree Snake: A Fact Sheet for Pacific Island Residents and Travelers [USGS-Fort Collins Science Center]
• Brown tree snake (Boiga irregularis) - Introduced Species Summary Project [Columbia University, Center for Environmental Research and Conservation]
• North American Brown Tree Snake Control Team (NABTSCT)
• Boiga irregularis (reptile) - ISSG Global Invasive Species Database [The World Conservation Union, Invasive Species Specialist Group]
  

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