The brown tree snake (Boiga irregularis) is a medium-sized rear-fanged colubrid with substantial color variation depending on its locality – brown, pale yellow, orange, striped brown/white and red/yellow. The red and yellow morph occurs here in the Top End and has earned the common name “night tiger” from its conspicuous color pattern. Boiga irregularis is a nocturnal hunter feeding primarily on birds and small mammals, but occasionally reptiles and frogs. In Guam this species is invasive and responsible for plummeting bird populations.
The head of Boiga is very similar to cat-eyed snakes (Leptodeira spp.) in the New World, but its overall morphology looks somewhat like a cross between a blunt-headed vine snake (Imantodes spp.) and Leptodeira. As arboreal snakes they are capable of supporting their entire body weight by less than one third of their body length, maneuvering with ease across very thin perches. Also, the night tiger’s pupils can independently dilate to adapt to different light conditions, something I noticed after shining my head torch on the snake. Snakes like this Boiga irregularis as well as water pythons (Liasis fuscus) and slaty-greys (Stegonotus cucullatus) can often be found crossing the road at night. Drive slowly and brakes for snakes!
Photographed after disturbance