'It's pretty incredible, the guy's got three legs': Watch lion looking for sex make record-breaking swim across treacherous river filled with crocs and hippos

A three-legged lion and his brother made a record-breaking swim across a river teeming with crocodiles and hippos in a desperate search for sex, researchers have revealed. The pair has now been seen traversing the treacherous Kazinga Channel in Uganda six times, including a nearly mile-long (1.5 kilometers) swim that was captured on film.

Jacob, one of the lions that made the record-breaking swim, lost part of his leg in a poachers trap. (Image credit: Alex Braczkowski)

This is believed to be the longest swim by a lion (Panthera leo) ever documented: Normally, lions' maximum observed swim distances are around 330 feet (100 meters). The Herculean feat is even more remarkable considering that one of the brothers is missing a limb. "It's pretty incredible, the guy's got three legs," said Alex Braczkowski, lead author of a study documenting the encounter.

"He was swimming [at a] much slower speed compared to [his brother]. But he made it," Braczkowski, a researcher at Griffith University in Australia and scientific director of the Volcanoes Safaris Kyambura Lion Project, told Live Science.

Cameraman Luke Ochse filmed the two lions — Jacob, who lost his foot in a poachers' trap, and Tibu — swimming across the channel that connects the George and Edward lakes on Feb. 1 with a drone carrying a thermal camera. The big cats initially attempted the swim three times (the first attempt captured in the footage above) but were forced to turn back after encountering either hippos (Hippopotamus amphibius) or Nile crocodiles (Crocodylus niloticus), both of which can kill lions in the water.

The study, which was partially funded by Northern Arizona University, is due to be published in the journal Ecology and Evolution.

Jacob and Tibu are in a precarious position in their homeland. The lion population in the region has been decimated over the last few decades, mainly driven by human-wildlife conflict and poaching, Braczkowski said. There are estimated to be around 40 lions left in the Queen Elizabeth National Park, and the population is under pressure from a sex ratio problem. In a healthy lion population, females outnumber males two to one. But among this Ugandan population, there are two times more males than females, putting huge pressure on the males to find a mate.

The brothers Jacob and Tibu are believed to have initially crossed the river in search of females, before losing fights to rival males and having to make a return journey. (Image credit: Alex Braczkowski)

The brothers made the initial swim because there were no females in their territory. They then had to make a return journey — which was captured on film — after a clash with two other groups of males. "They came in and were trying to challenge for territory and got their butts kicked," Braczkowski said. "So that's why they swam back."

Jacob and Tibu are closely monitored and are seen on a daily basis. Since the footage was captured, they have swum back across the channel once again on their quest for sex. "The guys are like 'screw it, we have to swim, we have to find females, this is the only way we're going to reproduce … it's either our genes live on or we die,'" Braczkowski said.