Scientists say they have observed wild chimpanzees tucking into an unusual snack: tortoises, whose hard shells they cracked against tree trunks before scooping out the meat.

Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig and the University of Osnabrueck said Thursday they spotted the behavior dozens of times in a group of chimpanzees at Loango National Park in Gabon.

It is the first time chimpanzees have been observed eating tortoises, with weaker animals often passing their prey to stronger adults who would break them open and share the meal.

Researchers said one male even ate half the tortoise, then tucked it into a tree fork and came back the next day to finish the leftovers, suggesting chimpanzees are capable of planning ahead.