We tend to think of snakes as dominant and dangerous, but they actually have a surprising number of natural enemies. Johan Marais discusses the animal kingdom’s biggest snake killers
Strangely enough, snakes have a lot of enemies, and for many species it is a real struggle for survival. Eggs and hatchlings are obviously particularly vulnerable.
There are many predators that eat snake eggs, with the water monitor lizard and veld monitor being major culprits. With their forked tongues, these monitors are highly efficient at locating snake eggs, and will quickly eat an entire batch.
Honey badgers, baboons, monkeys and bush babies are also fond of snake eggs.
Juvenile snakes are particularly at risk and are often taken by mammal carnivores, a variety of birds, monitor lizards and other snakes. Survival rates are often low as predators take out large numbers of small snakes.
Domestic cats are also a major problem and very good at killing small snakes. Unfortunately, cats are inclined to bring half dead snakes into the house, as they do with mice, and people occasionally get bitten while trying to rescue the snakes.
Different species adopt different survival strategies, with most young snakes keeping a very low profile and eating often to get bigger, and so reduce the number of predators that threaten them. Black mambas, for instance, are in the region of 50cm long when they hatch and keep a low profile while eating as much as possible. They are known to reach a length of 2m within a year. It is uncommon to see a black mamba less than a metre long, and of the hundreds that I have encountered and captured, only three have been under a metre.
Adult snakes also face a variety of predators, particularly birds such as hawks and eagles, secretary birds, ground hornbills and many more. Several mammals eat snakes, with honey badgers and mongooses being known as very efficient snake killers.
Honey badgers easily deal with adult snakes, but mongooses are not nearly as efficient at killing snakes as is often thought. In fact, most of the snakes that are taken by mongooses are juveniles.
It is unlikely that mongooses have any significant impact on snake numbers and, according to Prof Anne Rasa (author of Mongoose Watch) they are probably not major predators of snakes. It is certainly not true that there will not have snakes around if you are visited by mongooses. Actually, several snakes prey on mongooses, especially juveniles!
To my mind, the biggest threat to snakes is other snakes. There are several snakes that feed on other snakes. Most cobras, sand and grass snakes, file snakes and even the boomslang will eat other snakes if the opportunity arises.
In a puff adder study at Kwalata Reserve, Prof Graham Alexander of Wits University found that as many as half of the puff adders in the study were eaten by snouted cobras.
Twig snakes are also snake specialists and are particularly fond of green snakes of the genus Philothamnus – the Natal green snakes and green water snake. And it is not unusual for a snake to eat another snake longer than itself. The meal is just folded in a zig-zag shape as it is swallowed.
Snakes seem to be immune to their own venom and have a high resistance to the venom of other snakes. Snouted cobras often get bitten by puff adders but show few ill effects. The file snake is not venomous, yet it eats venomous snakes and does not bother to constrict them – it just swallows its prey half alive. – Johan Marais