On paper they're the unlikeliest of bedfellows. Spotted hyenas are known to jump at the chance to crunch a porcupine or warthog, both herbivores who don't stand a chance against the formidable predators. So how come they can share a home?
Researchers working in the Lewa Wildlife Conservancy in northern Kenya say they've found evidence all three mammals used the same den in two sites in a three-year period - and quite possibly the hyenas involved didn't eat up their bedfellows once they were all outside.
"We've been monitoring hyena dens for a long time, but we hadn't seen this before," said Marc Dupuis-Désormeaux, a conservation biologist from York University in Toronto, who is the lead author of the study published in the African Journal of Ecology.
A number of factors may have facilitated this unlikely cohabitation: a shared fridge, different bed-chambers and, crucially, the fact that at such close quarters the hyenas were no longer able to deploy their greatest hunting weapon - stealth.
Store of bones
The hyenas brought in ample supplies of bones which porcupines, despite being vegetarian, are also known to enjoy.
Although the scientists were not prepared to destroy the den by digging it up to determine the exact nature of the sleeping arrangements, their hunch is that each species occupies a separate branch or chamber.
"We were trying to imagine what it looks like inside," Dupuis-Désormeaux told RFI. "I can't imagine they're all holed up in one area."
Within such a confined space hyenas would be at a disadvantage, unable to mount surprise attacks as they might do above ground.
"They're just faced with a faceful of really nasty warthog tusks or porcupine spines," Dupuis-Désormeaux said.
Morgane Gicquel, a postdoctoral researcher who has studied spotted hyenas in Tanzania's Serengeti National Park but was not part of the Kenyan study, said adult hyenas often remain at the entrance cavity of a den but, because of their size, don't go any further.
"Only cubs and juveniles are small enough to enter [deeper into] the den," she said. Hyena cubs are not yet skilled hunters and therefore would not pose a threat to the cohabiting warthogs and porcupines, she noted.
Potential foes have been recorded concurrently sharing burrows elsewhere: foxes and mice in Japan; badgers, porcupines and foxes in Italy. But this is the first reported evidence of the phenomenon in Africa.
Freak occurrence?
The camera trap footage revealed that one of the hyena dens harboured two porcupines, three warthogs and seven hyenas; the other had two porcupines, six warthogs and 11 hyenas. The animals were entering via the same entrance, sometimes just minutes apart.
Typically, spotted hyenas will hunt and kill both porcupines and warthogs. In fact, elsewhere in the Lewa conservancy that is home to an estimated 125 spotted hyenas, the researchers found warthog hair in the droppings deposited by hyenas from different clans. No warthog hairs were found in pellets dropped at the cohabited dens, however, raising questions about the dietary preferences of certain hyena clans.
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"There are still lots of questions," said Dupuis-Désormeaux.
After the den-sharing was documented between 2016-2019, cohabitation was not recorded again in Lewa. This has left the research team wondering if it was a freak occurrence.
But Sarah Benhaiem, co-director of the Serengeti Hyena Project in neighbouring Tanzania, told RFI via email that she had observed warthogs in close proximity to communal dens used by spotted hyenas.
"On at least two occasions it was observed that hyenas shared their den with warthogs," she said.
