The brown vine snake Oxybelis aeneus is a colubrid snake originally described by Johann Wagler in 1824. It is one of three species in the genus Oxybelis, the other two of which are the short-nosed vine snake O. brevirostris and the green vine snake O. fulgidus. Oxybelis aeneus has one of the largest geographic distributions of any snake species, occurring from southern Arizona to southern Brazil. This species is very long and thin, and can be distinguished from similar looking snakes by its complete lack of green coloration, its diurnal cycle of activity, and its exceptionally long and narrow head. The venom of this species can cause paralysis or death in the small animals on which O. aeneus preys, but humans bitten by this species seldom experience symptoms worse than localized swelling or blistering. When disturbed, this species may perform a distinctive threat display, but it seems to prefer to hide or escape rather than fight if possible.