TO SNAFFLE ripe fruit before the competition, grey-cheeked mangabeys keep their eye on the weather. Not only can the monkeys remember how to find the trees where their favourite figs were ripening, they can also monitor the weather and return just as the figs are ready.
Karline Janmaat at the University of St Andrews, UK, made the discovery after tracking a group of between 18 and 26 mangabeys (Lophocebus albigena johnstonii) for 120 days in the Kibale Forest of Uganda. She found that whenever individual monkeys tested the ripeness of figs by squeezing and smelling them, they were more likely to revisit the tree if the weather warmed, accelerating ripening (Current Biology, vol 16, p 1212).
鈥淚t鈥檚 very competitive in the rainforest, so you would expect it would pay to be able to predict when fruit ripens so you can get there first,鈥� says Janmaat. 鈥淚t makes sense that the monkey evolved these cognitive skills.鈥�
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She says that even though temperatures varied on average by as little as 1 掳C the monkeys seem to incorporate it into foraging strategies. Geese and finches are known to time their arrival at food sites to coincide with plant cycles, but what makes the monkeys unique, Janmaat says, is their use of the weather to fine-tune their foraging techniques.
鈥淚t鈥檚 this flexible use of memory that makes it so special,鈥� says Janmaat, whose work is aimed at unravelling the roots of intelligence in humans and other primates.
