The hitchhiker’s guide to snakes
We have accurate distribution maps for all snakes that occur in South Africa. These are used in field guides and scientific publications, and they tell us where certain species are found naturally.
So, when a farmer tells me there’s a green mamba on his farm in Kuruman, I can confidently tell him that what he’s seeing is more likely a male boomslang. Green mambas are only found along the KZN coast, close to the sea.
However, from time to time, snakes do pop up in areas where they should not occur. It might be that their presence in a particular area was initially overlooked by scientists, like the black mamba in parts of the Northern Cape, but the most likely explanation is that these snakes are hitchhikers who have been unintentionally moved by humans.
Hitchhiking occurs when a snake is transported from one area to another as a stowaway with cargo, such as plants, bales of hay or firewood. It could also conceal itself somewhere in the engine or suspension of a vehicle. When the vehicle reaches its destination, the snake escapes, hundreds of kilometres from where it naturally occurs.
Hitchhikers seldom survive in their new habitat because it’s often unsuitable – the climate might be too harsh, or their natural prey is not readily available. Some hitchhikers end up in suburbia – in recent years, we’ve caught black mambas in places like Boksburg and Potchefstroom!
Another way for a snake to end up far away from its known distribution area is if it escapes from captivity. Non-venomous exotic species like American corn snakes, South American boa constrictors and West African ball pythons are sometimes caught in suburbs, as are venomous exotics like rattlesnakes and various cobras. (Exotic species should never be released into the wild.) Fortunately, hitchhiking and escaping are both not very common, which is surprising, especially when you consider the number of opportunities created by transport vehicles and campers in our country.
Still, always keep an eye out for uninvited guests in your vehicle next time you head into the bush… – Johan Marais