Common or mainland tiger snake (Notechis scutatus), black or island tiger snakes (N. ater)
Tiger snakes are found in the temperate areas of southern Australia, including Tasmania, where they are particularly large and venomous. Identification of tiger snakes by the presence of stripes is unreliable, since this varies with the seasons and the maturity of the snake, and there is also an unstriped black species (N. ater). Several other venomous and non-venomous Australian snakes may also be striped. Features of tiger snake envenomation include neurotoxicity (caused by pre-synaptic and post-synaptic neurotoxins), coagulopathy and rhabdomyolysis.
Mainland Tiger Snakes (Notechis scutatus)
Tiger snakes are solidly built, with broad, flattened heads. When disturbed, tiger snakes may flatten their necks in a threat display. They usually strike low to the ground. Average length is approximately 1m. Adults are usually banded, and colour may vary from pale yellow to almost black. Occasionally, the bands may be absent, leading to difficulties with identification. The fangs are usually around 3.5 - 5mm in length. Tiger snakes are ovoviviparous (holding the eggs in their abdomen until they hatch, and giving birth to live young). The average litter size is around 30. Tiger snakes are active on warm summer evenings, and are attracted to farms and outer suburban houses, where they hunt mice and rats, and where they may be trodden on by unwary people barefoot at night. They prefer swampy or marshy ground, and hunt frogs around creeks, rivers or dams.
This snake is distributed along the southeastern coast of Australia, including Victoria, eastern New South Wales, part of South Australia and Tasmania. This includes many of the most populous areas of Australia, and tiger snake bite is currently one of the most common snake bites in Australia, along with brown snake.
The venom is produced in large quantities, the average yield being around 35mg. The record yield was 180mg. Tiger snake venom contains pre-synaptic and post-synaptic neurotoxins, myotoxins and procoagulants. Bites result in paralysis, incoagulable blood and muscle damage, which may lead to renal failure.
Black Tiger Snakes (Notechis ater)
Black or island tiger snakes are quite distinct from mainland tiger snakes. 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.
Most live on islands off the south coast of Australia and Tasmania, although some have a limited range on the mainland. Black tiger snakes (Notechis ater occidentalis) are found in the southwest corner of Western Australia, and Krefft's tiger snakes (Notechis ater ater) live in a small area of the Flinders Ranges in South Australia. Peninsula tiger snakes (Notechis ater niger)are found on the Yorke and Ayre Peninsula and Kangaroo Island and neighbouring islands. 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.
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. Victims of envenomation by this snake should initially be treated with double the usual dose of antivenom, due to the copious amounts of venom produced. The toxicity of Chappell Island tiger snakes is less than that of the mainland tiger snakes, but that of the South Australian Island tiger snakes is more toxic than those of the mainland, with a similar average venom yield of 34mg. The components of the venom are similar to those of the mainland tiger snakes, causing paralysis, clotting deficits and muscle damage.