Brown Tree Snake
(Boiga irregularis)

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Invasive Status
Highly invasive Population increasing
Natural Range
  • Wallacea
  • New Guinea
  • North and east Australia
Introduced Range
  • Guam
  Accidental shipping  

Predation of native species

Damage to infrastructure

Predation of domestic animals

Removal Methods

Baiting and poisoning

Sniffer dog use on cargo 

The brown tree snake (Boiga irregularis) is a metre-long tree snake native to the bioregion of Wallacea.


Native RangeEdit

The brown tree snake is native to eastern Indonesia, New Guinea, north and east coastal Australia and the Solomon Islands. [1]

Introduced RangeEdit

The brown tree snake has breeding populations in Guam. [1]

It has also been sighted Texas, USA, the Northern Mariana Islands, the Marshall Islands, the Caroline islands, the islands of Wake Oahu, Okinawa and Diego Garcia Atoll but isn't thought to be established in any of these. [1]

The brown tree snake has also been seen in Hawaii multiple times, with 8 sightings between 1981 and 1998, although it is not thought that this species has established any breeding populations. [2]

Pathways and IntroductionEdit

The brown tree snake was first introduced to Guam in the 1950s. The snake was first sighted in Guam inland from the sea port and had spread across the island by 1968. It is thought that the snake was accidentally imported to Guam on ships from the Admiralty islands (specifically Manus Island***) on US military ships during World War II. The snakes may then have stowed away on planes, spreading the species accross the island quickly. [2]


The brown tree snake is responsible for multiple species extinctions by predation. The Guam rail and Micronesian kingfisher are both extinct (with 10 of Guam's 12 native bird species being removed from the island ([3]) ). Flying fox populations have also been decreased, with the Guam flying fox becoming extinct in part due to the brown tree snake. [1]

Brown tree snakes also cause power outages on the island by entering transformers or residual appliances or crawling on power lines. 1200 power outages have been caused by this since 1978. [1]

These snakes also occassionally kill poultry and pets and, although bites aren't fatal, the snake's venom can cause small children to fall severely ill. [1]

Control and Removal MethodsEdit

One removal method by poisoning involves dropping acetaminophen-laced rodent carcasses out of helicopters. Sniffer dogs are being used to check plane cargo for snakes to stop the species from spreading elsewhere. [3]


1 Introduced Species Summary Project

2 Hawaii Invasive Species Council

3 BBC News - "Battling the brown tree snake in Guam"