Biology of the Brown Treesnake

The Brown Treesnake (BTS), Boiga irregularis, is indigenous to areas west of the Wallace Line, which is west of the island of Sulawesi in Indonesia.  The BTS’s historic range runs east through Papua New Guinea to the Solomon Islands and south among the northern and eastern rims of Australia.

The BTS is thought to have been brought to Guam during or after World War II by military cargo ships or aircraft.  The BTS is highly prevalent on Guam since it has no natural predators.  This snake is highly adaptable to survive easily in almost any type of habitat, forest strata, altitudes or seasons with the exceptions of extreme dryness, bright sunlight, high daytime temperatures or freezing conditions.  The major natural factor that can limit the BTS population is the availability of prey.  This demographic “weak link” may offer opportunities for developing control measures.

A Brown Treesnake, which is primarily nocturnal, is searching for food at night.

The types of prey that BTS eat are small birds, bird eggs, and other small animals such as lizards and frogs.  A larger individual snake will sometimes attempt to eat a larger animal such as another snake or large bird.

Generally, BTS are three to six feet in length, sometimes growing up to 10 feet for some individual snakes.  Coloration ranges from lightly patterned brown to yellow/green and even beige. 

The reproduction of BTS is poorly understood.  The BTS females usually lay four to 12 oblong eggs in a clutch.

The BTS is slightly venomous, producing venom through two larger fangs on the back of the upper jaw.  Its venom is not considered dangerous to adult humans, but can be for small children.  The venom is used to subdue and kill small prey on which the BTS normally feeds.