Fancy a nighttime dip in a river teeming with crocodiles and hippos? Probably not. Yet, earlier this year in Uganda, two lions did just that. For the first time, scientists captured this astonishing and daring behaviour on film.
Led by Dr Alexander Braczkowski from Griffith University’s Centre for Planetary Health and Food Security, a research team used high-definition heat detection cameras on drones to film the duo crossing the Kazinga Channel in Uganda in the depths of the night.
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Impressively, one of the pair was a 10-year-old local celebrity Jacob the lion, whom Braczkowski described as “Africa’s most resilient lion”.
“He has been gored by a buffalo, his family was poisoned for lion body part trade, he was caught in a poacher’s snare and finally lost his leg in another attempted poaching incident where he was caught in a steel trap,” Braczkowski said.
Previous swims by African lions have ranged from 10 to a couple of hundred metres, and have resulted in several deaths from crocodile attacks. Not one to be outdone, Jacob and his brother, Tibu, swam over a kilometre, possibly even a kilometre and a half if changes in direction are taken into account.
Braczkowski added, “His swim across a channel filled with high densities of hippos and crocodiles is a record-breaker and is a truly amazing show of resilience in the face of such risk”.
The journey was anything but plain sailing. On their first attempt, Jacob and Tibu sensed something stalking them in the water. The pair split up, evading the unseen menace lurking beneath the surface, before eventually retreating to their starting point.
So, what could drive the brothers to take such an incalculably high risk? The chance of finding a mate… of course.
According to the researchers, competition for females in the Queen Elizabeth National Park that Jacob and Tibu call home is fierce.
“They lost a fight for female affection in the hours leading up to the swim, so it’s likely the duo mounted the risky journey to get to the females on the other side of the channel,” Braczkowski explained.
There is a bridge that connects the two river banks in the park, however, the presence of people was likely off-putting to the lions. It’s not surprising given Jacob’s past experience that he’d rather take his chances in the predatory river than bump into some of us.
“We need to know the drivers of decline and also to understand how lions are faring here over time," Braczkowski told BBC Science Focus. "The fact that our science has unlocked the problem of sex ratios clearly diagnoses the problem causing these kinds of extraordinary behaviours – the lions are swimming because they are searching for females in a male-dominated system.”
About our expert
Alexander Braczkowski has been running a long-term study of African lions and other predators in Queen Elizabeth and several other Ugandan National Parks. He is currently the scientific director of the Volcanoes Safaris Partnership Trust’s Kyambura Lion Project and has been working with the Ugandan Government since 2017 to build scientific capacity in the wildlife department to census lions and other predators. The paper detailing Jacob and Tibu's swim, ‘Long distance swimming by African Lions in Uganda’, has been published in Ecology and Evolution.
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