Forget bananas. In the forests of Kenya and Tanzania, some monkeys are looking to the skies for food.

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In a recent paper, scientists outline the first detailed observations of monkeys eating bats, and the behaviour could hold clues about how diseases like Ebola pass from species to species. 

Over a period of around six years, a team led by Elizabeth Tapanes from the Gombe Hybrid Monkey Project witnessed a total of 13 predation attempts on bats, and 11 successful kills, in the forests of Kenya and Tanzania.

“In two of the events at the Kakamega Forest in Kenya, a monkey snatched a bat from its day-roosting tree before eating it. Roosting bats were likely easy prey that could be reached while torpid or asleep,” Tapanes says in a statement. 

The bat-eating primates were Cercopithecus monkeys, a group known to be opportunistic omnivores (which means they’ll eat most things they can get their little hands on). Although the prey choice was unusual, it was not entirely surprising – and judging by the monkeys' behaviour at mealtimes, it seems flying food was a prized catch.

“During three cases of bat feeding, we observed monkeys exchange aggressive behaviour, including ... hits, chases, and/or aggressive growls. This behaviour seemed aimed at retaining or securing access to the bat carcass," explains Tapanes. 

While the team observed only a handful of such events per year, the discovery is important in that it may help explain how zoonotic diseases – that's diseases that can spread between animals and humans – "jump" between different species and eventually infect people. One such disease is Ebola, one of several lethal viruses that bats are known to harbour. 

"The most widespread Ebola epidemic to date has been hypothesised to have spread from a child playing in a tree inhabited by Mops condylurus, a common insectivorous bat found throughout sub-Saharan Africa," write the researchers.

But the path of infection isn't usually that direct. In the majority of cases, people become infected through contact with sick monkeys (or other non-human primates), so understanding how diseases spread to them first is important as scientists work to prevent future outbreaks. 

This latest research suggests monkeys may become exposed not just through eating fruits contaminated by bat saliva or faeces, but also through handling and eating the bats themselves. The researchers found that the monkeys spent up to an hour consuming a single bat, and in one case consumed the bones as well.

All of these encounters occurred near forest edges and other areas near human settlements, like plantations, so it's possible that the bat-eating behaviour is unique to such modified habitats. Further research is now needed to shed light on whether forest loss and other habitat changes caused by humans could be driving the monkeys to search for unusual food sources.

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Top header image: Peter Steward, Flickr