Chimps Time Their Breakfasts to Gather the Best Fruit

How do chimps acquire sufficient food during lean times? Scientists may have found out just that. It turns out that chimps make their sleeping nests en route to breakfast sites containing fruits that are more competed for by other daytime fruit-eaters than other fruits.

Not all tropical fruits are valued equally by rainforest foresters. In order to see whether chimps target their movements to obtain more desirable fruit, the scientists recorded when and where five adult female chimps spent the night and acquired food.

In the end, the researchers found that chimps left their sleeping nests earlier when breakfasting on very ephemeral fruits, especially when they were further away. This shows the lengths that the chimpanzees would go to in order to acquire preferred fruits.

"It was thrilling to see chimpanzee mums and their young carefully treading the forest floor during twilight, behaving skittish and on guard while moving towards their early morning breakfast figs," said Karline Janmaat, one of the researchers, in a news release. "One fifth of these mornings they left before sunrise and the rest of the forest seemed sound asleep. It got even more exciting when our analyses indicated that they were departing earlier when the figs were far away and that the females were likely making up for travel time to arrive before competitors!"

The researchers also found that the female chimps positioned their sleeping nests in the direction of the next day's breakfast sites with ephemeral fruit rather than in the direction of sites with other types of fruit. It appears that the chimpanzees were able to flexible plan their breakfast times.

The findings reveal that large-brain primates can buffer the effects of seasonal declines in food availability by working out timing to arrive to sites first.

"When following chimpanzees in the forest, I have always had the feeling they know much more than me," said Christophe Boesch, one of the researchers. "This study helps to clarify some parts of this feeling; chimpanzees before making their night nests to sleep were as well planning for their breakfast tree the next morning."