Species: Cebus libidinosus
Common Name: Black-striped capuchin
The genus Cebus is, currently, composed of eight species. I was not able to find out much about the black-striped capuchin – other than that it lives in Argentina, Brazil, and Paraguay. I have chosen it in place of it’s more widely known cogeners because of one unique trait.
Black-striped capuchins use tools in the wild:
“We confirmed that the monkeys were wild. We surveyed the area for lithic (stone) artifacts showing evidence of the nut-cracking activity,” said Fragaszy. From a blind built 15-20 meters from one of the nut-cracking sites frequented by the capuchins, Fragaszy and the team observed a group of wild capuchin monkeys (Cebus libidinosus). The area seemed to offer scarce food resources, especially in a dry season. It contained natural vegetation and, scattered across the site, boulders and exposed rocks that the capuchins used as anvils.
“We surveyed the area and measured the weight of the hammer stones. Our original estimate was 470 grams (16.6 ounces), but on our next trip, funded by National Geographic Society and the L.S.B. Foundation, we found that they were actually over a kilo. Adult capuchin monkeys weigh 3-4 kilos (6.6-8.8 pounds), so they are lifting a third and sometimes a half of their body weight!”
One of the more interesting things about capuchin tool use is that because of the size and strength needed to crack the nuts juveniles are unable to do this, so there is little in the way of teaching (unlike in chimps). As the above linked article puts it:
There is, however, one notable difference in the research on capuchin monkeys, according to Fragaszy. “There is no evidence of teaching. The juvenile monkeys share the propensity to explore objects in a percussive fashion, as children do. They explore, but they are not effective,” she said.
“The effective behavior only appears in mature capuchins. The juveniles are interested in the activity, they play lifting stones and pounding things, they try to crack one nut with another, but they are not strong enough to crack the nuts with the stones.”
There are a number of articles on capuchin tool use available should you wish to learn more…
Note added later: Cebus libidinosus is also referred to as a bearded capuchin, I suspect this is the correct common name rather than black-striped capuchin…