Brown tree snake

The brown tree snake (Boiga irregularis), also known as the brown catsnake, is an arboreal rear-fanged colubrid snake native to eastern and northern coastal Australia, eastern Indonesia (Sulawesi to Papua), Papua New Guinea, and many islands in northwestern Melanesia. This snake is infamous for being an invasive species responsible for extirpating the majority of the native bird population in Guam. It is also one of the very few colubrids found in Australia, where elapids are more common. The brown tree snake preys upon birds, lizards, bats, and mice and other small rodents in its native range. It preys on birds and shrews in Guam. Their presence threatens species of regional native birds and lizards such as the common sparrow. 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. The longest recorded length of this species is one found on Guam measuring 3 m (9.8 ft). The reproductive characteristics of the brown tree snake have not been widely studied. The female is known to produce 4 to 12 oblong eggs, long and wide with leathery shells. Females may produce up to two clutches per year depending upon seasonal variations in climate and prey abundance. The female deposits the eggs in hollow logs, rock crevices, and other sites where they are likely protected from drying and high temperatures. Populations on Guam may reproduce year round. The brown tree snake is a nocturnal, rear-fanged colubrid, possessing two small, grooved fangs at the rear of the mouth. 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 localized 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.