People often think hippos are herbivores with big smiling faces. Every now and then, reports of a hippo of hunting down prey, eating a carcass, or stealing prey from a crocodile are heard, but they're typically considered 'aberrant' or 'unusual' behaviour.
Now, however, a collaboration among researchers from 4 continents demonstrates that carnivory, or eating meat, is not uncommon among hippos at all, and that this behaviour may increase their susceptibility to mass mortality during anthrax outbreaks. Hippos, elephants, buffalo or antelope are often affected by anthrax epidemics, but anthrax outbreaks among hippos exhibit certain unusual characteristics that could be explained by consumption of the carcasses of infected animals - especially those of other hippos.
"The phenomenon of carnivory by hippos is crucial to an understanding of their susceptibility to this disease," said Joseph Dudley, co-author of the Mammal Review study.
"These reports fit the fact that hippos are the closest living relatives of whales, which are all carnivorous," added co-author Marcus Clauss.
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Joseph P. Dudley et al. Carnivory in the common hippopotamus : implications for the ecology and epidemiology of anthrax in African landscapes , Mammal Review (2016). DOI: 10.1111/mam.12056