Native to Australia, Papua New Guinea, and the Solomon Islands the brown tree snake was first found in Guam in the late 1940s or early 1950s. It has not established on the continental United States.

Arriving on imported cargo it began to prey on th native lizards and birds of the island. It has killed off most of Guam’s native forest birds. Brown tree snakes are active at night and are excellent climbers. The snakes also cause power outages by climbing on electrical wires.

Because of abundant prey and lack of natural predators, the population grew to the highest density of snakes ever recorded; at twenty or more snakes per acre of jungle.

As an adult the snake can reach lengths of ten feet, but most are three to four feet long. They are semiconstrictors and mildly poisonous and uses both poison and constriction to kill prey. The snakes will strike when aggravated but are not a danger to adult humans. Babies and young children are at risk and should recieve immediate medical attention if bitten.

To prevent its spread Wildlife Services traps snakes in high-risk areas and has snake-detecting dogs to check cargo. People leaving from Guam should check their belongings carefully.

(From: http://www.invasivespeciesinfo.gov/animals/bts.shtml and http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_wsbtsnake.html )