The story of the ‘Man-eaters of Tsavo’ has been retold through script, cinema, and oral tradition in the 100 years since their infamous ‘reign of terror’. Despite their predictably broad popular appeal, the details pertaining to the natural history of these lions Panthera leo have never been reviewed. The skulls and skins of these lions have resided at the Field Museum of Natural History (Chicago) for over 75 years. An analysis of the skull of the primary culprit displays a traumatic injury that may have limited his predatory ability in subduing ‘normal’ prey. A sample of hairs, reflecting the diet of both man-eaters, is preserved in the broken and exposed cavities of their canines. Various additional circumstances likely contributed to their man-eating habit. The Tsavo incident closely followed the debut of rinderpest on the continent, which devastated cattle and buffalo, the primary prey of the Tsavo lion. The Tsavo ‘nyika’ consists of a dense thorn scrub thicket limiting visibility and passage, representing an ideal habitat for an ‘ambush predator’. Finally, historical review of the literature reveals that ‘man-eating’ was not an isolated incident at Tsavo. This behaviour was well established in the vicinity of the railway bridge well before these infamous lions appeared, and continued well after their demise, suggesting a recurring opportunity, which may have evolved into a local behavioural tradition. In sum, virtually all of the recognised preconditions for man-eating outbreaks to occur were in effect at Tsavo in the 1890's.
