One of the World’s Rarest Antelopes

Until their partial translocation to Tsavo East in 1963, the sole surviving population of the critically endangered hirola antelope (also known as Hunter's hartebeest) was found near the Kenya–Somalia border in the south Tana River and Garissa districts. Intense poaching (for meat) and habitat destruction have reduced their numbers from an estimated 14,000 in 1976 to fewer than 5000 today.

A 1995 survey found that the original Tsavo East translocated population of 30 had grown to at least 76 hirola. The following year, 29 further hirola (including six pregnant females) were introduced into the park, although the latest survey, taken in 2011, put the total Tsavo East population back at 76. With no captive population anywhere (save for a breeding population of around 50 in a predator-proof sanctuary) further north at Ishaqbini, the future of the hirola remains precarious – according to the International Union for the Conservation of Nature (IUCN), 'the loss of the hirola would be the first extinction of a mammalian genus on mainland Africa in modern human history'.

They can be difficult to spot in Tsavo East – your best chance is in the little visited southern reaches of the park. The hirola resembles a hartebeest in size and form, but has a distinctive white line marking between the eye, rising to a small peak on the forehead between the horns.

Man-Eaters of Tsavo

The famed ‘man-eaters of Tsavo’ were among the most dangerous lions to ever roam the planet. During the building of the Kenya–Uganda Railway in 1898, efforts soon came to a halt when railway workers started being dragged from their tents at night and devoured by two maneless male lions.

The surviving workers soon decided that the lions had to be ghosts or devils, which put the future of the railway in jeopardy. Engineer Lt Col John Henry Patterson created a series of ever more ingenious traps, but each time the lions evaded them, striking unerringly at weak points in the camp defences. Patterson was finally able to bag the first man-eater by hiding on a flimsy wooden scaffold baited with the corpse of a donkey. The second man-eater was dispatched a short time later, although it took six bullets to bring the massive beast down.

According to Patterson’s calculations, the two lions killed and ate around 135 workers in less than one year. He detailed his experiences in the best-selling book The Man-Eaters of Tsavo (1907), which was later rather freely filmed as Bwana Devil (1952) and The Ghost and the Darkness (1996).

Patterson turned the two man-eaters into floor rugs. In 1924 he finally rid himself of the lions by selling their skins to the Chicago Field Museum for the sum of US$5000. The man-eaters of Tsavo were then stuffed and placed on permanent display, where they remain to this day.

Hypotheses vary as to why these lions became man-eaters. Tsavo lions have noticeably elevated levels of the male sex hormone testosterone. The pair themselves also had badly damaged teeth, which may have driven them to abandon their normal prey and become man-eaters. An outbreak of rinderpest (an infectious viral disease) might have decimated the lions’ usual prey, forcing them to find alternative food sources. One final theory is that the man-eaters may have developed their taste for human flesh after growing accustomed to finding human bodies at the Tsavo River crossing, where slave caravans often crossed en route to Zanzibar.

Tsavo's Maneless Lions

The lions of Tsavo have an image problem. For a start, they're known as man-eaters, thanks to the rather prolific man-eating exploits along the under-construction Kenya–Uganda Railway at the dawn of the 20th century. And then there's the issue of their manes: male Tsavo lions are known for their less-than-fulsome manes, with even fully grown and dominant males looking like subadult lions – their unkempt, scraggy manes are a far cry from those you'll see elsewhere, in the Masai Mara or Nakuru, for example.

The growth of a mane in a male lion signifies to the rest of the lion world that it has reached sexual maturity, associated as it is with testosterone. According to a study carried out by Dr Craig Packer, one of the world's foremost lion experts, the fuller and darker the mane, the more likely a male lion is to attract female lions looking for a mate. Male lions with longer, darker manes are also more likely to have offspring that survive for longer and are most likely to win male-on-male fights.

So why do Tsavo males, renowned as they are for their ferocity, have such inadequate manes? No-one knows. Some theories suggest that climate is to blame – heavy-maned lions suffer in the heat and lighter, thinner manes could be an evolutionary adaptation for lions living in hot climates. But male lions in similarly dry regions, such as the Kalahari Desert of southern Africa, have almost-universally impressive manes. West African lions, too, have similarly ragged manes to those of the Tsavo males, suggesting some possible link in the distant past. But no such link has yet been proven and whatever caused this genetic predisposition to less-than-hirsute facial profiles for now remains a mystery.