Scientists Capture Lions’ Record-Breaking Swim in Crocodile-Infested Waters

Aerial heat detection of Jacob and Tibu being stalked crossing the river. Credit: Alexander Braczkowski

Two lion brothers, Jacob and Tibu, undertook a daring kilometer-long swim across Uganda’s Kazinga Channel, braving dangers like crocodiles and hippos, captured by high-definition thermal cameras. Their motivation likely stemmed from a failed competition for mates, illustrating the extreme measures lions take to survive in increasingly human-affected areas.

Two lion brothers’ record-breaking swim across a predator-infested African river has been documented in a study co-led by Griffith University and Northern Arizona University.

Dr. Alexander Braczkowski, from Griffith’s Centre for Planetary Health and Food Security, led a team that filmed a two-male lion coalition crossing the Kazinga Channel in Uganda at night, using high-definition heat detection cameras on drones. The work was done under the supervision of the Uganda Wildlife Authority.

One half of the lion brother duo was a 10-year-old local icon known as Jacob, who became famous for surviving a multitude of life-threatening incidents, one of which left him with an amputated leg.

“Jacob has had the most incredible journey and really is a cat with nine lives,” Dr. Braczkowski said.

Jacob the lion. Credit: Alexander Braczkowski

“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.

“The fact that he and his brother Tibu have managed to survive as long as they have in a national park that has experienced significant human pressures and high poaching rates is a feat in itself — our science has shown this population has nearly halved in just 5 years.

“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.”

Previous reported swims by African lions have ranged from 10 to a couple of hundred meters, some of which resulted in deaths by crocodile attacks.

The big swim prompts a key question: why did Jacob and Tibu risk the dangerous kilometer-long night swim in the first place?

“It’s likely the brothers were looking for females,” Dr. Braczkowski explained.

“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.”

Jacob and Tibu. Credit: Alexander Braczkowski

“There is a small connecting bridge to the other side but the presence of people was probably a deterrent for them.”

Dr. 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.

This behavioral observation is a direct symptom of some of his previous research, highlighting skewed sex ratios in lion populations.

“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,” Dr. Braczkowski said.

Reference: “Long-distance swimming by African lions in Uganda” by A. Braczkowski, L. Ochse, B. Atukwatse, O. Cornille, C. O’Bryan, P. Lindsey, R. Kotze, L. Gibson and D. Biggs, 10 July 2024, Ecology and Evolution.
DOI: 10.1002/ece3.11597