Â鶹ÒùÔº

Scientists in Brazil recently recorded evidence that a jaguar visited an isolated island in the reservoir area of the Serra da Mesa Hydroelectric Power Dam in northern Goiás State. The same jaguar had been identified on the mainland, 2.48 km away from the island, back in 2020. Both instances were recorded by camera-trap stations, three on the mainland and one on the island, which were set up for an exploratory jaguar survey. The specific jaguar's identity was confirmed by spot-pattern analysis.

After analyzing possible aquatic trajectories for the jaguar, the researchers found that it had two possible paths. Either the jaguar swam the direct 2.48 km to the island, or used a stepping-stone-like islet, taking a 1.06 km swim, followed by a 1.27 km swim to get to the island.

Previous records indicated a maximum swimming distance of around 200 meters for jaguars. Given the possible paths here, this jaguar had to swim a minimum of 1.27 km, possibly more, shattering previous records. This impressive feat is documented in a new bioRxiv , in which the researchers involved also discuss a newly proposed aquatic-cost scale for assessing the ecological connectivity between landmasses.

It was previously thought that reservoirs, like Serra da Mesa, acted as absolute barriers for large carnivores due to prior instances of predator collapse on islands further than a kilometer away from the mainland. Yet, genetic studies across the Amazon River indicated only partial segregation, suggesting occasional crossings.

The study authors explain, "These rare events suggest that, under favorable conditions (e.g., warm water, low currents, presence of stepping-stone islands), large felids may occasionally exploit aquatic corridors that appear to be initially insurmountable."

The research team proposes a new ordinal aquatic-cost scale for modeling connectivity between landmasses, described by low/medium/high cost ranking for water crossings. Low cost was defined as less than 300 m; medium as 300–1,000 m with stepping-stones; and high as greater than 1,000 m of open water. This scale is meant to help inform future hydropower impact assessments and corridor planning for jaguar conservation.

"Historically distributed from the southwestern United States to northern Argentina, the species has lost approximately 50% of its original range due to habitat conversion, fragmentation, and perpetuity. Like other large carnivores, jaguars depend on dispersal to sustain gene flow, avoid inbreeding, and recolonize vacant habitats," the authors write.

While jaguars and other large animals may occasionally be capable of overcoming manmade barriers for food or mating reasons, they still face many challenges with ecosystem loss. Jaguars are apex predators and are crucial for ecosystem balance, but they have already lost about 50% of their range. Further research can help quantify how often these long-distance crossings occur and test the new cost scale in other systems.

The study authors point out a need for smarter infrastructure planning to protect biodiversity. They say, "Because some reservoirs are at least partially permeable, conservation planning should consider amphibious corridors that integrate riparian habitat with aquatic stepping-stones. Maintaining gentle shore gradients, preserving riparian vegetation, and safeguarding islets ≤1 km apart can reduce swimming costs for jaguars and other taxa."

© 2025 Science X Network