Tuesday, January 18, 2011

Venomous Snakes: the Elapids

Australia’s venomous snakes are all proteroglyphs, meaning they all have rigid, hollow fangs at the front of the mouth; as opposed to the vipers and asps, which have mobile or folding front-fangs.  The proteroglyphs are all placed in the family Elapidae, including all of Australia’s deadly species, in addition to the cobras of Asia and Africa, kraits and sea snakes.   130 species of elapid occur in Australia.
These include the Black Snakes, Brown Snakes, Tiger Snakes, Broad-Headed Snakes, Taipans, Whipsnakes, Crowned Snakes, Death Adders, Shovel-nosed Snakes, Hooded Snakes, Bandy-Bandys and Sea Snakes … just to name a few!
Australia’s elapids also include the top ten deadliest snakes in the world:  three of which happen to be those most commonly handled at SnakeSense.
Such vast numbers are too great to tackle here, hence we will focus on four species with which we – and our clients – are most familiar.  For inhabitants of south-eastern Australia, these are the little friends you’re most likely to find in your garden.

Tiger Snake

Tiger Snakes (Notechis scutatus) exhibit phenotypic plasticity, which, put simply, means their genetic code is extremely flexible in terms of the superficial looks it can produce. Hence, Tiger Snakes are possibly the hardest snake for inexperienced folk to identify.  They can have stripes, as their name indicates – but many do not.  They can be brown, caramel, grey, black, golden … or even one superb young lady we once met, who was a bold yellowy-green with brilliant yellow stripes!   The ventral surface (underside) can be anything from cream to grey to yellow. In short, never judge a Tiger Snake by its stripes (or lack of them)!
Similarly, they can be small – even as adults – or extremely large, but the average size is 1m in length and 400g in weight.
They do have consistently large, somewhat stubby heads which are slightly distinct from the neck, compared to the other species sharing their natural range, with whom they might be confused, who have smallish heads flowing seamlessly into the neck.  A tiger can flatten out its neck (or in the case of the green/yellow starlet, most of her body) just like a cobra.
Tiger Snake crossing a road: never run over snakes.Tiger Snake crossing a road: never run over snakes.

Like their looks, Tigers are fairly flexible in their habits.  They are primarily frog eaters, but will happily adapt to just about anything which is on the menu, and can do a wonderful job reducing feral mouse and rat populations – and, in the case of particularly large individuals, will even eat young rabbits.
They are amongst the most arboreal of the Elapids, and will climb into trees and rooves if food beckons, although they are almost always found in close proximity to freshwater of some kind. They give birth to live young, making them ideally suited for life in the cool-temperate climates of southern Australia whether the weather is frequently too cold and unpredictable for the reliable incubation of eggs.
Tiger Snakes are found from south-eastern Queensland through eastern and coastal New South Wales to Victoria, where they inhabit all but the driest parts of the State.   Isolated populations are found in Tasmania; the Flinders Ranges; along the South Australian coast; in the south-western corner of West Australia and on numerous islands along the south coast.
They are calm, intelligent snakes, making them both clever and entertaining to work with.

Highland and Lowland Copperheads

Highland Copperheads (Austrelaps ramsayi) are common in cool upland areas in north-eastern Victoria and south-eastern New South Wales, being replaced by Lowland Copperheads (A. superbus) in southern Victoria, and Tasmania.
Highland Copperhead Austrelaps ramsayiHighland Copperhead Austrelaps ramsayi
Highland Copperheads gave rise to the mythical “Yellow-Bellied Black Snakes”, with dark grey to matte black backs and bright white to creamy yellow ventral scales (although some Tiger Snakes also have this appearance).  They have medium-sized heads with very distinctive white bars between the scales around the lips and nose.  Contrary to their name, they don’t always possess coppery heads, but often sport a narrow coppery stripe across the neck, like a collar.  They rarely exceed 1m in length, and are fairly fine-bodied.
Lowland Copperheads are more likely to have coppery heads, and the barring along the lips is much finer and paler than the Highland.  Their colouration is more variable, however, ranging from pale to dark shades of grey or brown.  They can grow up to 1.8m long and be particularly chunky if the going’s good.
Like their closely-related cousin, the Tiger Snake, both species are found near water and preferentially feed on frogs, skinks and small snakes – even of their own species.  They give birth to live young.
In our experience, copperheads are very nervous, jumpy snakes, and disappear quickly at the first sign of trouble.

Eastern Brown Snake

Eastern Browns (Pseudonaja textilis) are the blond bimbos of the snake world.  Anxious and generally panicky, they will cringe in a hole and stay there for hours if they think there’s something scary outside…
Courtesy of It's A Wildlife Photography Nature and Wildlife Photogrpahy Pty LtdCourtesy of It's A Wildlife Photography Nature and Wildlife Photogrpahy Pty Ltd
Found throughout Queensland, NSW and Victoria, they are almost always a variation of brown, from greyish to bright caramel, although some near-black individuals have been observed.  They have small, delicate heads, pretty brown eyes and a pale creamy underside with occasional brown speckles.
Thriving in agricultural areas, Eastern Browns love to eat mice and rats, and will be found in drier habitats than the other species listed here.  Unlike the other species of elapid found in Victoria, Eastern Browns are egg-layers – making them the most southerly distributed egg-laying snake in Australia.

Red-Bellied Black Snake

Anyone can identify this species: they are always perfect, glossy, jet black with bright red or pink ventral colouring extending slightly up the lower flanks.  Large animals, Red-Bellied Black Snakes (Pseudechis porphyriacus) can reach 2m in length, and have elegant, gently rounded heads.
Red Bellied Black Snake exiting hideoutRed Bellied Black Snake exiting hideout
Distributed throughout central and eastern Victoria and NSW, south-eastern Queensland and along the central to northern Queensland coast, this species is found close to dams, swamps and creeks, and may often be seen as a narrow wake progressing steadily across the surface.  They eat frogs, eels, fish, lizards and small snakes.  The Red-Bellied Black Snake is the only member of the black snake family which gives birth to live young: an adaptation which has allowed this species to live further south, in much cooler climates than its close relatives.  This species evolved live-bearing independently of other live-bearing lineages.
Red-Bellied Blacks are calm, almost laid-back animals.  They do not overreact easily, and tend to be extremely patient with the antics of snake-catchers, up until the point of capture, when they give the impression of being deeply offended.

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