The Brown Tree Snake (Boiga irregularis), also known as the brown cat snake, is a species of 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. They are very adaptable snakes and have been introduced to islands like Guam, from military transports in the 1940s. These snakes are also very aggressive, mildly venomous, and is infamous for being an invasive species responsible for extirpating the majority of the native bird population in Guam, like the Guam rail and Guam kingfisher.
In addition to birds, brown tree snakes will also prey on bats, moonrats, tarsiers, small rodents like rats, and lizards like geckos in the snake's native range, as well as shrews in Guam.