Scientists Find Monkeys Who Know How to Fish

By Carolyn Johnson

Long-tailed macaque monkeys have often made the news for grabbing fruit from the hands of curious zoo visitors. Their usual diet in the wild comes from foraging for crabs and insects, or eating fruit from the jungle.

Now researches at The Nature Conservancy have reported that groups of long-tailed macaques have been observed along rivers in East Kalimantan and North Sumatra provinces four times over the past eight years scooping up small fish with their hands and eating them along. Scientists claim that this is rare and isolated behavior limited to these monkeys in these areas.

Erik Meijaard, one of the authors of a report on the fishing macaques that appeared in the International Journal of Primatology, said that researchers are excited to discover a new behavior after studying the monkeys for decades. "It’s an indication of how little we know about the species," Meijaard says. Scientists say that although they don’t know what prompted the macaques to go fishing, it demonstrates one of their characteristics that is well-known—their ability to adapt to shifts in their environment and changing food sources.

"They are a survivor species, which has the knowledge to cope with difficult conditions," says Meijaard. "This behavior potentially symbolizes that ecological flexibility." Other primates that have exhibited fishing behavior include chacma baboons, olive baboons, Japanese macaques, orangutans, and chimpanzees.

Agustin Fuentes, a University of Notre Dame anthropology professor who studies long-tailed macaques, said he was pleased to see the finding announced to the public because this sort of information can offer insight into the complexity of long-tailed macaques and their habits and behaviors. Fuentes has observed similar behavior in flooded paddy fields in Bali, where he saw long-tailed macaques foraging for frogs and crabs. The observation reinforces his belief that the ability of the monkeys to thrive in urban and rural environments could be helpful in understanding how to preserve endangered species.

Fuents and Meijaard both say that further research is needed to understand what led the monkeys to go fishing, and how common it is among the species. "It was not surprising to me because they are very adaptive", Fuentes said. "If you provide them with an opportunity to get something tasty, they will do their best to get it."