The jaguars' ingenious new behavior was recorded by a World Wildlife Fund (WWF) study on a remote island off the Brazilian coast.
A thriving population of jaguars living on a small, unspoiled island off the coast of the Brazilian Amazon has learned to fish in the sea to survive, conservationists discovered.
The Maracá-Jipioca Ecological Station island reserve, three miles north of the state of Amapá, acts as a nursery for jaguars, according to WWF researchers who have trapped three felines and installed 70 camera traps in the remote jungle island.
Although jaguars have previously been seen catching fish in Brazil's Pantanal wetlands, this is believed to be the first evidence that the elusive creatures have been jumping into the sea to catch prey.
"This is the first time this behavior has been observed in the Amazon," said Marcelo Oliveira, WWF Brazil's senior program officer, who is leading the NGO's first investigation on the jaguar. "On the way out, the jaguar was dry and on the way back it was wet and it had a moving fish in its mouth." He believes that a large proportion of his diet is probably fish.
Oliveira said that jaguars have two fishing techniques: one is to wait for the tide to come in and fish in the ponds that form between the mangroves, and the other is to jump into the sea. "I do not know of any other population of jaguars that eats so much fish, it is very unusual," he added.
The 600-square-kilometer island, which is protected by the International Union for Conservation of Nature (IUCN), has no human residents and animals have little contact with people. It has a diverse landscape of tropical forests, flooded grasslands, dense coastal mangroves, and salt marshes.
It is also a stopping point for various migratory birds, including flamingos, ospreys, and American cuckoos. Fishermen say they have seen jaguars, as well as deer, anteaters and buffalo, swimming between the island and the mainland.
There are 27 jaguars on the island and five to six cats per 100 square kilometers in some parts. Normally only two to five jaguars would share a territory of this size. The island's jaguars are believed to hunt deer, buffalo, lizards and monkeys, but an abundant source of fish could be the secret to their success, the researchers say.
Iranildo Coutinho, head of the island's ecological station, describes it as a “kind of nursery or sanctuary” for jaguars because it may be feeding populations on the mainland. “Fishermen often say that the island produces jaguars. It is the only coastal island along the Amazon coast and that is why it contains very important samples of coastal fauna and vegetation that are very well preserved and act almost like a living laboratory, "he said.
The continental area adjacent to the island is dangerous for jaguars, as there are several buffalo herders who feel threatened by the presence of the cats. In late 2018, a female jaguar was killed with her cub after attacking dogs in the town of Sucuriju, 30 miles (50 km) from the island.
Jaguars are near threatened according to the IUCN red list, with steep declines caused by deforestation and the illegal wildlife trade, which attacks them for their skin and body parts.
The Amazon is the largest remaining stronghold for jaguars, but recent wildfires are estimated to have destroyed the habitats of 500 individuals. These cats are one of the largest predators in South America and are often viewed as a litmus test for the forest's health.
Satellite technology installed on the jaguar collars in Maracá-Jipioca provides researchers with hourly updates on the animals' movements. Camera traps have already taken more than 30,000 photos. Understanding how a predator uses its territory will help researchers learn how to limit unavoidable conflicts with humans.
WWF conservationists also collected blood samples from the collared jaguars to determine if they are crossing to the mainland to breed; otherwise, they are likely to have a very small genetic pool, which could pose a problem for the long-term health of the population.
Dr Chris Carbone, a senior researcher at the Zoological Society of London and an expert on predator-prey relationships, said the research (in which he was not involved) shows just how versatile these cats are. "It is good to see jaguars showing such adaptability, as wildlife in general is increasingly exposed to reductions in their habitats and this adaptive capacity may be critical to the future survival of such populations," he said.
“That said, we must not be complacent. We do not know how long jaguars have been fishing on these islands. If it is a long-standing behavioral adaptation, many species may experience changes in their habitats that are too sudden to allow them to adapt. "
The research is being conducted in collaboration with the Jaguar Conservation Fund and the Chico Mendes Institute for Biodiversity Conservation. Jaguar conservationist Lailson Ferreira, who works with WWF on the island, said: “It is important to preserve this island because this place is a treasure. There are very special creatures here, like the spotted jaguar and many others ”.
Oliveira added: “Months of meticulous planning went into the mission, but we can never guarantee a collar from a wild animal. Having three jaguars on this first WWF expedition is a surprising result.
"The satellite technology installed in the collars provides us with hourly updates on animal movements for up to eight months, resulting in a bank of information on how jaguars use the forest to live and thrive."
Next year, researchers are setting up more camera traps and in June 2020 they will set up two more jaguars.