The Brown tree snake (Boiga irregularis) is an arboreal colubrid snake native to eastern and northern coastal Australia, Papua New Guinea, and a large number of islands in northwestern Melanesia.

This snake is infamous for being an invasive species responsible for devastating the majority of the native bird population in Guam.^[1]

Diet

The Brown tree snake preys upon birds, lizards, bats and small rodents in its native range.^[2] It preys on birds and shrews on Guam.^[3]

Due 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 meters in length.^[2] The longest recorded length of this species is one found on Guam measuring three meters.^[2]

Reproduction

The reproductive characteristics of the Brown tree snake have not been widely studied.^[2] The female is known to produce 4-12 oblong eggs, 42-47 mm long and 18-22 mm wide with a leathery shell.^[2] Females may produce up to two clutches per year depending upon seasonal variations in climate and prey abundance.^[2] The female deposits the eggs in hollow logs, rock crevices, and other sites where they are likely protected from drying and high temperatures.^[2] Populations on Guam may reproduce year round.^[4]

Venom

The Brown tree snake is a nocturnal snake that can be very aggressive when confronted.^[2] It is a rear-fanged colubrid, possessing two small, grooved fangs at the rear of the mouth.^[5] Due to the placement of the fangs and grooved rather than hollow fangs, the venom is difficult to convey into a bite on a human, thus is only given in small doses. The venom appears to be weakly neurotoxic and possibly cytotoxic with localized effects, but these effects are trivial for adult humans, and serious medical consequences have been limited to children due to their low mass.^[2] This snake is still not considered dangerous to an adult human.^[5] The venom seems to be primarily used to subdue lizards, which are more easily positioned in the rear of the mouth for venom delivery.^[2]

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Invasive species

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.^[2][5] As a result of abundant prey resources on Guam and the absence of natural predators outside of feral pigs and Mangrove monitors, Brown tree snake populations reached unprecedented numbers.^[2] 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 domestic birds and pets; and considerable emotional trauma to residents and visitors alike when snakes invaded human habitats with the potential for envenomation of small children.^[2] Since Guam is a major transportation hub in the Pacific, numerous opportunities exist for the Brown tree snakes on Guam to be introduced accidentally to other Pacific islands as passive stowaways in ship and air traffic from Guam.^[2] To minimize this threat, trained dogs are used to search, locate, and remove brown tree snakes prior to the departures of outbound military and commercial cargo and transportation vessels from the island. ^[6] Numerous sightings of this species have been reported on other islands including Wake Island, Tinian, Rota, Okinawa, Diego Garcia, Hawaii, and even Texas in the continental United States.^[7] An incipient population is probably established on Saipan.^[2] Paracetamol has been used to help eradicate the snake on Guam. ^[8][9]

References

The Brown tree snake (Boiga irregularis) is an arboreal colubrid snake the lives in parts of coastal Australia, Papua New Guinea, and islands in northwestern Melanesia.

This snake is known for being an invasive species, responsible for killing the bird population on Guam.

Diet

The Brown tree snake eats birds, lizards, and bats. It also eats small rodents in its home.^[1][1] It also eats birds and shrews at Guam.^[2]

Due to the amount of prey and lack of predators in habitats such as Guam, they have been known to grow to larger sizes than their normal 1 to 2 meters in length.^[1] The longest recorded length of this species is one found on Guam was three meters.^[1]

Reproduction

Reproduction has not been looked at in detail.^[1] The female makes 4-12 eggs, 42-47 mm long and 18-22 mm wide with a leathery shell.^[1] Females make up to two groups, called clutches per year depending on season, climate. and amount of prey.^[1] The female places the eggs in hollow logs, rock cracks, and other places where they are likely protected from drying and high temperatures.^[1]

Venom

The Brown tree snake is a nocturnal snake that can be very aggressive when confronted.^[1] The fangs are grooved rather than hollow fangs, the poison is hard to place into a bite on a human, in this way, is only given in small amount. The venom appears to be weakly neurotoxic and possibly cytotoxic. Adults are not affectly in a great way, however, children are in greater danger.^[1]

References