How to ID a snake
One of the first factors any expert will consider when asked to ID a snake is the location. Where was the snake seen? Distribution is very important when it comes to identifying snakes. Many species only occur in certain areas, and so once you know the location you can rule out several other species which might confuse the issue. A large black snake in the Western Cape cannot be a Black Mamba and is more likely to be a Mole Snake or Black Spitting Cobra, as Black Mambas only occur on the warmer eastern half of the country. It could also be a very dark Cape Cobra.
Scales also play an important role in identification. Are they keeled or smooth? This question can rule out a lot of options and help clarify the identity. If a clear view of the snake is obtainable – either in person (without jeopardising your safety) or by means of a photograph – scale counts can be done. Head scales are important and are often unique for a species. Most digital cameras can zoom well and clear photographs of the side of the head can be captured. This will allow one to look at the upper labial scales, the pre- and post-ocular scales as well as the temporal scales. In many groups, such as the green and bush snakes of the genus Philothamnus, the number of temporal scales and the number of upper labials making contact with the eye are key in telling them apart. Scale counts are also very useful for small black snakes such as Stilettos, Purple-glossed Snakes, Wolf Snakes and Natal Black Snakes.
Both the colour and markings on some snake species vary dramatically throughout their range. Once you have an idea of what these colours could be, it makes identification easier. Some species always have a certain colour trait – such as a light upper lip – which can differentiate them from other similar looking species.
Knowing a bit about a snake’s behaviour also comes in handy when identifying it. For instance, Slug-eaters tend to curl up in tight balls when threatened, and Egg-eaters coil and uncoil – rubbing their keeled scales together to create a hissing sound. Herald Snakes often flatten their heads to expose their brightly coloured lips when in a defensive posture, and cobras form impressive hoods when cornered in an attempt to deter their attacker. There are exceptions to the rules of behaviour, and we occasionally see Mole Snakes lifting their heads off the ground and even flattening their necks, making them easily mistaken for a cobra. Such behaviour can be learned by observing wild snakes, reading up on the ASI Snake Profiles, or studying the Complete Guide to the Snakes of Southern Africa by Johan Marais.
ASI – Snake Rescue Association
African Snakebite Institute