Due to an accidental introduction after the events of World War II, this snake is now infamous for being an invasive species responsible for extirpating the majority of the native bird population in Guam.

The brown tree snake is a nocturnal and arboreal species that uses both visual and chemical cues when hunting, either in the rainforest canopy or on the ground.

[3] It is a member of the subfamily Colubrinae, genus Boiga, which is a group of roughly twenty-five species that are referred to as "cat-eyed" snakes for their vertical pupils.

The snake is long and slender, which facilitates its climbing ability and allows it to pass through tiny spaces in buildings, logs, and other shaded locations, where it seeks refuge during daylight.

[5] Owing to the availability of prey and lack of predators in introduced habitats such as Guam, they have been known to grow to larger sizes than their normal 1 to 2 m (3.3 to 6.6 ft) in length.

Weinell et al. found significant DNA differences between the Sulawesi and Sundaland populations, proposing in 2021 that all members west of Weber's Line be designated B.

In Papua New Guinea, it occupies a wide variety of habitats at elevations up to 1,200 m.[9] It is most commonly found in trees, caves, and near limestone cliffs, but frequently comes down to the ground to forage at night.

It hides during the day in the crowns of palm trees, hollow logs, rock crevices, caves, and even the dark corners of thatched houses near the roof.

[2] The female deposits the eggs in hollow logs, rock crevices, and other sites where they are likely protected from drying and high temperatures.

[18] In the northern Australian city of Darwin, the brown tree snake is significantly more likely to be encountered in suburban areas during the wet season months of January–March.

[20] This is indicative of shifts in snake behaviour or movement across the year, and may partially be driven by differences in seasonal detection probability.

[21] Due to the placement of the fangs and their grooved rather than hollow architecture, the venom is difficult to convey into a bite on a human, and thus is only delivered in small doses.

The venom appears to be weakly neurotoxic and possibly cytotoxic with localised effects that are trivial for adult humans; serious medical consequences have been limited to children, who are more susceptible because of their low body mass.

[2] Shortly after World War II, and before 1952, the brown tree snake was accidentally transported from its native range in the South Pacific to Guam, probably as a stowaway in ship cargo or by crawling into the landing gear of Guam-bound aircraft.

[2][21][22] As a result of abundant prey resources on Guam and the absence of natural predators apart from the native Mariana monitor and feral pigs, brown tree snake populations reached unprecedented numbers.

Snakes caused the extirpation of most of the native forest vertebrate species; thousands of power outages affecting private, commercial, and military activities; widespread loss of people's pets; and considerable emotional trauma to residents and visitors alike when snakes invaded human habitats with the potential for envenomation of small children.

[2] To minimise this threat, trained dogs are used to search, locate, and remove brown tree snakes before outbound military and commercial cargo and transportation vessels leave the island.

The study suggested that snakes living under stressful conditions such as high population densities or low prey resources had suppressed reproduction at multiple stages, including steroidogenesis and gametogenesis.

The decline in snake population may be identified as a result of depleted food resources, adult mortality, and/or suppressed reproduction.

The Guam National Wildlife Refuge is attempting to prevent the extinction of additional bird species endangered by the snake.

Furthermore, the introduction of the brown tree snake has had an indirect, negative impact on vegetative diversity as its intense predatory nature has decreased populations of vital pollinators including native birds and fruit bats.

[33] The outages, depending on the scale, can cause millions of dollars of revenue loss to Guam and can affect either the whole island or smaller parts of it.

[34] Due to the success of the brown tree snakes on Guam, there have been many efforts to both eradicate the invasive population and to prevent its spread to other places such as the mainland United States and other islands such as Hawaii.

The use of mice as bait has shown considerable reduction effects when combined with acetaminophen, to which the snake is particularly sensitive, in a mark-recapture experiment leading to potential widespread application in Guam.

[36] When utilising a precisely defined treated plot with results corrected for immigration and emigration, the additive effect of both acetaminophen and mice usage shows a 0% survival rate of the brown tree snake.

[38] An investigative study was performed to find predators of the brown tree snake that could possibly serve as a population control method.

[39] One reason for this conclusion was that the identified actual predators of the brown tree snake are generalist feeders and would cause further detriment to other native island species.