Snakes: Venomous or Non-Venomous
The shape of its head and its colouration do have some bearing on identification, but to assume a snakes identity from these traits alone can have disastrous consequences.
Two species: Tropidechus carinatus (rough scaled snake) and Tropidonophis mairii (keelback) both grow to approximately 900mm, both have strongly keeled scales, both have large eyes and round pupils, both have the same dark irregular bands, both occur along the East coast and Northern tropics and what's more they favour the same habitats. Here's the punch line, one is a harmless colubrid, the other a dangerously venomous land snake. So which is which?
Well, you could try counting the body scales. For instance, if a snake has no more than 23 rows of scales then it's a venomous snake, if it has between 23-30 rows of scales then it's a colubrid, if a snake has more than 30 rows of scales it's a python, and finally if it doesn't fit into any of these categories you're possibly dealing with an earth worm or a skipping rope.
To suggest that you count the rows of scales present on a wild snake you've just encountered to determine if it's dangerous or not, is I realise down right absurd. If you're close enough to count it's scales then you're close enough to be bitten, and really the only time a snake can be truly dangerous is when you're close enough to be bitten by it!
Even expert collectors have been known to miss-identify snakes, in fact just before publishing this blog, the Coffs Coast Advocate reported an incident whereby snake catcher Bruce Dwyer mistook a rough scaled snake for a colubrid and was bitten twice before crashing his car after loosing consciousness. He was rushed to hospital in a serious condition.
Unfortunately there exists no definitive tool to aid you in separating the venomous from the non-venomous snakes; not the shape of the head, the colour of it's back, nor it's inclination for tree climbing. By all means learn about the snakes that occur in your region, but remember if you're not an expert, it's probably best to assume all snakes you see as potentially dangerous and leave them well alone.
Photo courtesy of J. SULLIVAN / Ribbit Photography