Notechis ater humphreysi is found on King island and most of the Bass Strait islands, and the large Notechis ater serventyi is found on Chappell Island and Badger Island. Most black tiger snakes prefer marshy areas, and are active in the day. Island tiger snakes eat mostly mutton birds, and often use their burrows. Notechis ater are usually black, with paler abdomens. Banding is sometimes seen in Western Australian subspecies, but is uncommon in other subspecies.
Size is highly variable.
Chappell island tiger snakes are generally the largest, and may reach 2.4m. Krefft's tiger snake rarely exceeds 0.9m. Young black tiger sakes are born alive. Litters vary from 20 to 30. The Chappell Island tiger snake is the most prolific venom producer of all the black tiger snakes, with an average venom yield of 74mg, and a maximum recorded yield of 388mg.