Cracking this nut will take strength, skill and a grasp of physics – and the capuchin is equal to the task.
The monkeys choose nuts that are easiest to crack. An individual finds a groove in a log where one fits snugly, placing the flattest surface of the nut face down so that it’s stable. Then it chooses a heavy stone, raises it above its head and hammers the nut with force.
The behaviour is considered one of the most complex forms of tool use by non-human species, putting them on a par with chimpanzees.
This alpha male, weighing 4.2 kilograms, is using a 3.5 kg stone to break into a piassava nut in Fazenda Boa Vista, Brazil.
He was photographed by Luca Antonio Marino, a biology student at Roma Tre University in Rome, Italy, who studied the foraging strategies of wild capuchins for his master’s thesis.
Sam Wong - New Scientist