Once again, the Mystery of the Tsavo Lions Solved

I'll never forget my first lion.

A colleague and I had just arrived in the Semliki Valley, in the Congo, to a part of that valley then known as the most predator-rich region of Africa, with loads of lions and heaps of hyenas. Lots of leopards too. We arrived at the main base camp for a large expedition that I was to join a year later (this was a brief visit) and were told to find the satellite camp, out in the bush.

"Ten clicks that way, then a left on their road. Good luck finding the road."

Good luck indeed. Took us forever. And, at one point, after night fell, we had the brilliant idea that we could stand on the hood of of the Land Rover and maybe see lights in the distance (this turns out to have been totally worthless, as the camp was down in a valley, very far away, they mainly had candle light, and by this time only a single hurricane lamp would be burning, invisible from this distance).

So, we stopped, and I got out of the Land Rover, climbed up on to the hood, and just before the driver switched off the headlights, a giant lioness walked up to the truck, right in the headlight beams, looked at me, sniffed at the grill of the truck, and wandered off into the blackness of night, now invisible to us.

She was was about ten feet tall, fifty feet long, and had fangs about a foot long.

OK, I'm exaggerating slightly, but here's the thing. You see a giant cat, like a lion or tiger, in a zoo, in the enclosure, and that's one thing. You see a giant cat in the wild, a wild giant cat, not a tame one, and it is close enough to reach over and take your leg off without going anywhere, and that's a different thing.

That was not to be my first close call with lions, nor the closest in fact, over the next year and a half. And, though I was not eaten by a lion, something like six people were, right near that spot.

Between this short trip and the later, much longer visit to this site, a lion, it is said, started eating people. It was local villagers, living in the usual wattle and daub grass-roofed huts who were being eaten. Lions tend to go for the head region when they kill, but they usually attack much more robust prey, like a large antelope or a buffalo. So, when the take a human, they may crush the head in such a way that an eye ball or two pops out. I was told that in a few of the locations where the lion ate someone, all that was left was an eye ball or two, and that freaked the freaken heck out of the people in those tiny villages.

I was told this by a local Greek merchant named Andre, who happened to be the guy with the biggest and most accurate firearm in the region, who, with his brother, took out the lion. Andre was wearing a nice neckless he had made himself, using one of the canines of the lion. His brother, he told me, had a matching neckless.

So, what about Tsavo? You may remember "The Ghost And The Darkness," which was a book and a movie, or you may have heard about them from another source. It is an old story.

Back when the British were building a railroad across what is now Kenya, during much of the year 1898, two lions took to dining on the mostly Chinese rail workers. The number of victims they are said to have eaten ranges up to 135 people (see: The Man-Eaters of Tsavo and Other East African Adventures), and the lions were said to be mysterious and demonic. The reality is a bit different. They are known to have eaten 28 railway workers, and they were just regular lions, but of the mainless variety found in that region.

Lions, like cats generally, tend to be specialists. The way to find, trap, and kill (and sometimes, to process or eat) a particular species involves a lot of important detail. They way a Zebra vs. a Buffalo can kick you to death if you are a lion matters. The way to entrap a Ugandan kob vs. a wildebeest are not even close to the same thing, if you are a lion. Lions, therefore, tend to hunt a particular prey, or a small number of possible prey type, for a long time, possibly their entire lives.

Putting this a different way, the list of prey lions are known to have fed on is long. The list of species you actually observe a given pride of lions to feed on, if you watch most of their kills for many months, is very short. Humans are totally on the long list, and of all the wild mammals that kill humans in Africa, lions kill the most. But humans are rarely on the sort list. Why? Because they taste bad to lions, right? That's what everyone says. Unfortunately, that is not true. We taste just fine, if a bit stringy. But we are bad prey for other reasons. First, we are rare. Yes, yes, seven billion is a lot, but in lion country, we are rare. Second, we live inside hard to get into nests much of the time, so it is not really worth it. Third, lions are not idiots. We have sharp weapons and sometimes guns, so even if a lion can easily sneak up on a human, some other human is going to stick or shoot you. In any event, once a lion starts to eat humans, it does not live too long. The Tsavo lions probably lived longer than the average man eater. The Semliki man eater emerged on the scene, ate some people, and was dispatched between my visit in late August and my return the following June.

But there is some new research telling us a few cool things. Here's the paper:

DeSantis, L.R.G. and B. D. Patterson. 2017. Dietary behaviour of man-eating lions as revealed by dental microwear textures. Scientific Reports 7, Article number: 904 (2017) doi:10.1038/s41598-017-00948-5.

Here is the abstract:

Lions (Panthera leo) feed on diverse prey species, a range that is broadened by their cooperative hunting. Although humans are not typical prey, habitual man-eating by lions is well documented. Fathoming the motivations of the Tsavo and Mfuwe man-eaters (killed in 1898 in Kenya and 1991 in Zambia, respectively) may be elusive, but we can clarify aspects of their behaviour using dental microwear texture analysis. Specifically, we analysed the surface textures of lion teeth to assess whether these notorious man-eating lions scavenged carcasses during their depredations. Compared to wild-caught lions elsewhere in Africa and other large feliforms, including cheetahs and hyenas, dental microwear textures of the man-eaters do not suggest extreme durophagy (e.g. bone processing) shortly before death. Dental injuries to two of the three man-eaters examined may have induced shifts in feeding onto softer foods. Further, prompt carcass reclamation by humans likely limited the man-eaters’ access to bones. Man-eating was likely a viable alternative to hunting and/or scavenging ungulates due to dental disease and/or limited prey availability.

You need to know that at Tsavo, at that time, the prey was very reduced in frequency because of a drought and the rinderpest. So some lions were probably desperate. In the case of Tsavo, one lion had a tooth problem, which may have made killing larger and more formidable prey difficult, and the other lion was apparently its friend and went along with it. (Male lions do form such small teams.) Other research at Tsavo indicated that these lions had eaten more people than recorded by the railroad, so they may have been eating humans for a while, though not their entire adult lives.

There are two other writeups on this work you will want to check out:

Virginia Morell, "Why did these lions eat 35 men?"

Bem Giaromp "Why did the Tsavo lions eat people?"

See also: Michael Torrice, "A body count for two man-eating lions"