Food-finding tests in five lemur species show that fruit-eaters may have better spatial¹ memory than lemurs with a more varied² diet. The results support the idea that relying on foods that are seasonally³ available and far-flung gives a competitive edge to individuals with certain cognitive⁴ abilities -- such as remembering where the goodies are.

 

In a study appearing in the journal Animal Cognition, researchers Alexandra Rosati at Yale University and Kerri Rodriguez and Brian Hare of Duke compared spatial memory skills across five species of lemurs living in captivity⁵ at the Duke Lemur Center -- fruit-eating red-ruffed and black-and-white ruffed lemurs, leaf-eating Coquerel's sifakas, and ring-tailed and mongoose lemurs that eat a mix of fruit, leaves, seeds, flowers, nectar（花蜜，甘露） and insects.

 

A total of 64 animals took part in the studies, which measured their ability to remember the locations of food treats in mazes⁷ and boxes. The results are consistent with these species' foraging⁸ behavior in the wild, the researchers say, with fruit-eaters doing well and omnivores lagging behind.

 

In the first experiment, the lemurs learned the location of food hidden in one of two arms of a T-shaped maze⁶. A week later, the fruit-eating ruffed lemurs were the only species able to retain and recall the right spot.

 

A second experiment tested whether the lemurs were recalling the exact spot or just remembering the turns they took along the way. First the lemurs learned how to find a piece of food hidden in one wing of a symmetrical cross-shaped maze. Ten minutes later, the lemurs were moved to a new starting position in the maze and released to find their way again.

 

The ruffed lemurs were most likely to set off again to the right spot in the cross-maze, even though they had to take new turns to get there. "Before they might have turned right, but now they had to turn left to get to the same spot," Rosati said.

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