The odds were against the pair from the outset. Having lost a battle for territory, they were trapped in inhospitable surroundings with the nearest females on the other side of the channel.
When they heard the roar of lionesses, they couldn’t resist. But it took them time to pluck up the courage and embark on their journey. They initially jumped out of the water immediately after getting in and were forced to turn back again after being chased by a hippo or a crocodile, according to signals the team picked up with an overhead drone.
Then, nearly an hour after their first foray into the channel, the big cats tried again.
“It was pretty dramatic,” Dr Braczkowski, who works with Griffith University in Australia and Northern Arizona University, told the New York Times. “It looks like two tiny little heat signatures crossing an ocean.”
Braczkowski has little doubt it was the lure of the lionesses on the other side of the river which prompted Jacob and Tibu to undertake the perilous journey.
“These males and these swimming events are a symptom of this problem,” he said.
“The males are not finding females in the area where they had tenure. The only females they can get to may be across the channel.”
Lion expert Craig Packer, who was not involved in the study, agreed.
“If there’s nobody to mate with, what are you doing? You’re a male lion. You don’t have a very long lifespan, so you have to get on with it, especially if you’re wounded.
“If they can tell that there are females over there and no males, it would be, ‘Sign me up! Sign me up!’”
Jacob, one of Uganda’s tree-climbing lions, has come close to death at least four times in the past,
He has been snared, trapped, poisoned and even gored by a buffalo. He lost a leg when he was caught in a wheel trap in August 2020 in
Virunga National Park, in the Democratic Republic of the Congo.
Having been treated by vets, Jacob somehow worked out how to get around on three legs, joining the rest of the pride as they roam around the park.
Fitted with a radio-tracking collar, his movements have been followed by the Uganda Wildlife Authority, which is ready to come to Jacob’s aid if he runs into trouble again.
Lions do not like water. They are known to have swum in the Okavango Delta in Botswana but over far more modest distances.
They have little option there because the delta is subject to seasonal floods. According to experts the Okavango lions are adept at avoiding the deepest parts of the river.
Other sightings of swimming lions have occurred in Zambia, Zimbabwe and Tanzania.
Until Jacob’s and Timu’s marathon, the furthest lions have swum is believed to be just under 1km from the shore of Lake Kariba, on the Zambia-Zimbabwe border to one of the islands.
