Before dawn in northeastern Brazil, Noemi Spagnoletti and her colleagues left camp for the sandstone hills where wild bearded capuchins slept. They aimed to reach the monkeys by 7 a.m. and followed them until sunset, sometimes seeing little more than patches of fur or a tail slipping through the foliage.
The researchers rarely witnessed the moment a monkey captured its prey. More often, they spotted one already holding a lizard, rodent, or bird. They could then watch which parts it ate first. The monkeys often started with the brain and internal organs before moving on to muscle. Sometimes, they left the rest behind.
A study published in PLOS One found that bearded capuchins hunted small animals more often when fruit and other plant foods were harder to find. The pattern may offer insight into how human ancestors got enough to eat when the foods they normally relied on ran low.
“What surprised me most was the extent to which vertebrate predation was integrated into the capuchins’ daily lives. When I first started observing them, my main interest was their use of tools, and I certainly did not expect vertebrate predation to become such an important part of what we were documenting,” Spagnoletti, co-lead author of the study, said in a PLOS interview.
Explore All OptionsWhat Bearded Capuchin Monkeys Hunt and Eat
From May 2006 to December 2010, researchers followed two groups of monkeys at Fazenda Boa Vista in northeastern Brazil. One group was given nuts, corn, and water each day as part of another project, while the other had to find all of its own food. Over 5,093 hours, the team recorded 446 times when the monkeys ate vertebrates.
“It was a demanding field effort, but it was also an extraordinary experience. We spent long days immersed in the Cerrado, in many ways living alongside the monkeys and experiencing their environment with them,” Spagnoletti said.
Of the 281 times researchers made notes about what the monkeys were eating, most involved lizards or rodents. The monkeys also ate birds, snakes, marsupials, bats, and an iguana. These were the first records of bearded capuchins eating opossums, iguanas, bird eggs, or nestlings.
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Why Capuchin Monkeys May Eat Brains and Organs First
The monkeys often ate nearly all of a bird. When they caught a mammal, they ate its tail, paws, and sometimes its eyes. They ate lizards and geckos almost entirely, including the skin, appendages, brains, and organs. Males hunted more often than females and were the only monkeys seen eating snakes, usually after removing the head.
Brains and organs are rich in fat and other nutrients, according to earlier research. By eating those parts first, a monkey may have reached the fattier tissues before another monkey could take the carcass. The researchers did not test that idea. Muscle was tougher and took longer to pull apart and chew.
The monkeys generally hunted and ate alone, but the researchers also saw them hunt together and pass meat to one another.
Capuchin Hunting and Human Evolution
The monkeys that found all their own food ate vertebrates about 1.9 times as often as the group fed each day. They also ate more animals when less fruit was available, though more prey may have been around at certain times of year.
Capuchins cannot tell us exactly what human ancestors ate. But they show how a mostly plant-eating primate may hunt for meat when its usual foods run low.
Fossil sites about 2 million years old contain signs that hominins ate small animals. The team hopes future studies will compare the marks capuchins leave behind with those on ancient bones.
“One of my current focuses is understanding the cultural diversity of animals and exploring how behavioral traditions that vary among populations can be better recognized as part of biodiversity. In the longer term, I hope this can contribute to developing conservation approaches that take animal cultural diversity into account alongside species and genetic diversity,” Spagnoletti said in the interview.
Article Sources
Our writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:
- This article references information from a study published in PLOS One: Small vertebrate consumption by capuchin monkeys (Sapajus libidinosus): Insights into the human predatory pattern
- This article references information from an interview published by PLOS One: Interview with Noemi Spagnoletti, PhD, Global Mammal Assessment Lab, Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy
