Reptiles & Amphibians
Despite their reputation, the vast majority of East Africa’s 650 reptile and amphibian species pose no threat to humans, and their ecological value cannot be overstated. Snakes play an important part in rodent control, while lizards and frogs devour mosquitoes and other pesky flying insects, and crocodiles are the aquatic equivalent to vultures, disposing of the carrion that might otherwise clog up East Africa’s lakes and rivers.
- The Nile crocodile, with its armoured scales and toothy mouth, is the largest surviving descendent of the gigantic predatory archosaurs that once roamed the earth, growing to lengths of up to 8m, weighing more than 1,000kg, and with a lifespan comparable to humans. The Selous’s Rufiji River harbours some gargantuan specimens, but decent numbers are also present in Serengeti, Ruaha and Katavi. Although it feeds mainly on fish, the Nile crocodile can down an animal as large as a wildebeest, as commonly occurs when the Serengeti migration crosses the Mara and Grumeti rivers. Humans are vulnerable too - assume that bathing in any Tanzanian lake or river is unsafe, and always maintain a metre’s berth from the shore.
- Often seen motoring in the slow lane of game reserve roads, the leopard tortoise, named for its domed gold-and-black mottled shell, might occasionally weigh up to 40kg. Freshwater terrapins are flatter than tortoises, and often sun themselves on partially submerged rocks or logs. Five endangered turtle species have been recorded off the Tanzanian coast, with the green, hawksbill and olive ridley turtle all breeding on its beaches.
- Snakes are seldom seen on safari and rank far lower on the list of potential hazards than many people suppose – statistically, car accidents and malaria pose far greater threats, as to a lesser extent do lightning strikes! The rock python, a non-venomous species that strangles its prey, is Africa’s largest snake and one of the more regularly observed species. Of the venomous species, the puff adder of rocky savannah has a notoriously sluggish disposition that means it is more often disturbed by humans than other snakes. Also well represented are the venomous cobras and mambas, but the majority of Tanzania’s are non-venomous colubrids and pose little threat to any living creature much bigger than a rat. A remarkable colubrid is the rhombic egg-eater, which can dislocate its jaws to swallow an egg whole.
- Of almost 200 lizard species recorded in Tanzania, none is venomous, though the 2-3m monitor lizards might bite if cornered. Conspicuous species include the colourful agamas, often seen sunning on koppies in the Serengeti, and the endearing common house gecko, a bug-eyed, translucent white lizard that scampers up walls and upside-down on ceilings in pursuit of insects. Tanzania is the most important centre of chameleon speciation after Madagascar, with 11 endemics listed among three dozen species, most of them associated with relatively inaccessible forests in the Eastern Arc Mountains.
- East Africa harbours at least 200 frog species, whose calls often form the best way of identifying similar species. Calling is most vigorous after rain, when safarigoers are sometimes treated to an unforgettable dusk chorus of guttural croaks, high whistles, and the wondrously ethereal popping chorus of the bubbling kassina, which is most vocal during April-May. Habitat loss, wetland degradation and industrial pollution have resulted in a sharp global decline in amphibian populations, and while East Africa is less affected than more industrialised regions, a quarter of its frog species are on the IUCN red data list.
