History

The brown tree snake is believed to have been introduced via cargo transported by U.S. military ships during World War II. On Guam, there are up to 13,000 snakes per square mile. The first sightings were in the early 1950s. Brown snakes became a common sight throughout central Guam by the 1960s, and by 1968 were found throughout the island.

Biology

The snakes begin to reproduce around age 3, depositing as many as 12 eggs once or twice a year in caves, hollow trees, and other areas chosen for their protection from drying and overheating. The eggs are abandoned and hatch within 90 days. The snakes live in trees and shrubs, coming out at night to feed. The adaptable creatures invade holes and buildings in urban habitats while searching of food and hiding spots. The nocturnal species seeks shelter from the Sun during daylight hours.

Ecology

Brown tree snakes will feed upon birds, lizards, small mammals, bird and reptile eggs, and small common household pets. The snake has come close to wiping out the native forest birds of Guam, including the flightless rail. The brown tree snake is responsible for the disappearance of twelve species of birds unique to Guam.

Impact

Since 1978, more than 1,200 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.

Control

Brown snakes are preyed upon by pigs and monitor lizards, although not frequently enough to significantly lower the snake population on Guam. There are no large-scale methods available for eradication other than traps, visual inspections, trained dogs, and specialized barriers. Toxicants and bio-control are currently in development.

References on the Web:

Invasivespecies.gov

Brown Tree Snake

Global Invasive Species Database

Patuxent Wildlife Research Center