We Thought Jaguars Could Only Swim 200 Meters. We Were Wrong.

Big cats have all manner of impressive skills, from being the apex predator to the ancestor of modern humans, to surviving in all manner of habitats. Now a jaguar has broken a record by swimming six times the previous distance thought to be possible for the species.

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In central Brazil, camera traps recorded a jaguar (Panthera onca) on the mainland in April 2020 and then later on a forested island in August 2024. To reach the island the jaguar must have crossed an artificial lake. The individual was a male and is recognized in the camera trap photos by its distinctive spot pattern. 

The researchers found two possible routes for the individual to have taken across the Serra da Mesa Reservoir. The first is a direct swim of nearly 2.5 kilometers (1.5 miles); and the second, two shorter swims of 1.06 km + 1.27 km each with an islet between them. While there is no evidence the jaguar used the islet, the team think the minimum longest distance the jaguar swam was 1.27 kilometers (0.7 miles), nearly six times the previous known longest distance for swimming for this big cat species. 

Jaguars are the largest big cat in South America but have lost around 50 percent of their original range from the southwest United States into Argentina. For their survival they depend on having large areas for dispersal to prevent inbreeding and maintain genetic diversity. While jaguars are powerful apex predators and known to be good swimmers, their capabilities in the water are somewhat understudied, with only anecdotal evidence of them swimming 200 meters (656 feet). 

Hydropower and dam development has led to barriers in jaguar habitat, but this new research suggests jaguars have a greater ability to cross wider rivers and streams, suggesting that these barriers are more permeable than first thought.

Other big cats like lions have also made record-breaking swims across large rivers. These choices reflect the idea that when the ecological pressures are strong enough, these powerful big cats can negotiate large bodies of water. 

The paper is available on the preprint server bioRxiv and has not yet undergone peer review.