Possibly in search of lionesses, two lion brothers swam 1.3 kilometres across an African river known to be infested with hippos and crocodiles, making it the longest documented swim for African lions with visual evidence.

Facing fierce competition for lionesses and having lost a fight for female affection in the hours leading up to the swim, the brother duo was driven to embark on the perilous journey, likely to get to females on the other side of the channel, according to the authors of the study published in the journal Ecology and Evolution.

They filmed the lions trekking their way through the Queen Elizabeth National Park in Uganda before crossing the Kazinga Channel, using heat cameras on drones.

Threatened by human pressures and high levels of poaching, the Panthera leo species' population has been shown to have nearly halved in just five years.

One of the lion brother duo, whom the researchers named Jacob and called a local icon, is famous for having survived multiple life-threatening events.

"I'd bet all my belongings that we are looking at 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," author Alexander Braczkowski from Griffith University, Australia, which co-led the study, said.

In one of the video footage accompanying the study, Jacob can be seen limping and leading the way for his brother, Tibu, through the national park, before approaching the shore.

On February 1, 2024, the lion brothers begin moving along the water's edge and entering water. They can be seen making three attempts at crossing the channel, each time swimming a certain distance, before encountering a likely threat -- an animal or a current, and being forced back to the banks.

On the fourth attempt, the brothers finally succeed in swimming across, reaching the Katunguru region of the park on February 4.

While an amazing show of resilience, the lions' swim, an attempt in search of homes and partners, is a direct symptom of skewed sex ratios in lion populations, the authors said.

"Jacob and Tibu's big swim is another important example that some of our most beloved wildlife species are having to make tough decisions just to find homes and mates in a human-dominated world," Braczkowski said.

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