Video: Lion brothers filmed swimming through crocodile-infested water to avoid humans

Two lion brothers have been filmed making a perilous 1-kilometre (0.6-mile) swim across Uganda's Kazinga Channel, a river teeming with predators.The lion brothers, Jacob and Tibu, embarked on their nighttime journey across the channel, in what has become the first visually documented long-distance swim by African lions (Panthera leo).

The swim included several false starts and was fraught with danger, as potential predators were recorded trailing the lions before they successfully reached the other side.

Researchers used heat-detecting drone cameras, in collaboration with the Uganda Wildlife Authority, to track their movements.

"Lions are known to hunt both crocodiles and hippos on occasion, but when in water they themselves become vulnerable," the researchers noted in their published paper. "River crossings in Africa come with considerable risk of injury, or even death, from encounters with the much larger Nile crocodile or hippopotamus."

Jacob, a 10-year-old lion well known to local experts, has a remarkable history of survival. He has endured poisoning by poachers, a goring by a buffalo, and the amputation of one of his legs after being caught in a poacher's trap. "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," said Alexander Braczkowski, the study's lead author and a conservation biologist from Griffith University in Australia.

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The journey of Jacob and Tibu was likely driven by the search for mates. But this tale of romantic courage points to a more troubling narrative about the impact of poaching and human encroachment on the lion population in Queen Elizabeth National Park.

"Our science has shown this population has nearly halved in just five years," Braczkowski added.

While a safer route across a road bridge exists, conservationists believe the lions avoided it due to the presence of people and security forces. Instead, researchers have observed lions opting for the far riskier lake channel crossing, filled with crocodiles and hippos, on six occasions.

"Competition for lionesses in the park is fierce, and 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," explained Braczkowski.

The research has been published in the journal Ecology & Evolution.

(With inputs from agencies)