Practical information to identify and manage non-native, invasive plants and animals
The Quiet Invasion:
A Guide to Invasive Species of the Galveston Bay Area
Brown tree snake
Boiga irregularis

ITIS TSN:174206
Presence:Species of Concern
Habitat:Terrestrial
Native Range:Indonesia, the Solomon Islands, New Guinea, and Australia
Human Health
This species can be aggressive when cornered. This species is classified as mildly venomous in Guam. No known fatalities have occurred.
Prohibited Lists
As of 2010, this species is not prohibited by the TPWD.
Introduction Pathways
It is believed that this species has been transported via container ships and aircraft in shipments of cargo.
Geographic Distribution
This species has been introduced to the U.S. territory of Guam. In 1993 a brown tree snake was found in Corpus Christi, Texas in a shipment of cargo from Guam (McCoid et al. 1994). As of 2010, this species is not reported in Texas.
Specific Primary Habitats
The brown tree snake occurs in a wide variety of habitats and environments, including tropical evergreen forests, mangroves, grasslands, and shrub lands. In Guam the brown tree snake is found in all terrestrial habitats, but is especially common in forests and human-modified environments. It is also known to inhabit agricultural areas, coastal habitats, forests, grasslands, riparian zones, scrub/shrub lands, urban areas, and wetlands (ISSG 2006a).
Ecological, Economic, or Social Impact
The brown tree snake is an effective predator of small vertebrates, including birds and lizards. The brown tree snake has decimated bird populations in Guam. The species also causes frequent power outages by climbing onto power lines and wooden poles (USGS Date unknown) and is a noted agricultural pest (ISSG 2006a).
Physical Description
The brown tree snake is a slender snake with large eyes and a large head. It is light brown, yellowish olive to greenish brown in color, sometime with black speckling. The pupil of the eye is vertical. The brown tree snakes are typically 1-2 meters in length but may grow to 3 meters (ISSG 2006a). This species is a climbing snake that can lift three-fourths of its body off the ground, using the remaining quarter for support (USGS Date unknown).
Reproduction Characteristics
Female brown tree snakes lay eggs in clutches of 10 or greater in their native range and in clutches of five in Guam. In ideal conditions this species reproduces year-round, but in temperate environments reproduction is seasonal. Females may be able to store live sperm for several months (ISSG 2006a).
Feeding
The brown tree snake is known to feed on birds, lizards, amphibians, small mammals, bird and reptile eggs and small pets. Juveniles mainly feed on lizards and amphibians while adults prefer relatively larger animals (ISSG 2006a).
Control
Since early detection is key to preventing the spread and establishment of this species, regional/local monitoring or surveillance is essential. Cargo from invaded areas (such as Guam) should be thoroughly inspected.

This species belongs to the following lists:
Images
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Head and characteristic eyes of the brown tree snake (<i>B. irregularis</i>). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Head and characteristic eyes of the brown tree snake (B. irregularis). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Adult brown tree snake (<i>B. irregularis</i>). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Adult brown tree snake (B. irregularis). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Adult brown tree snake (<i>B. irregularis</i>). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Adult brown tree snake (B. irregularis). Photo courtesy Gordon Rodda, U.S. Geological Survey, Bugwood.org.
Page Updated/Reviewed: 07/14/2010 10:58 AM
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