The win-stay rule in foraging decisions by free-ranging titi monkeys (Callicebus cupreus cupreus) and tamarins (Saguinus imperator imperator and Saguinus fuscicollis weddelli)

Rainforest primates need to apply distinct foraging rules for efficiently using the spatial knowledge of the distribution of resources showing different temporal patterns of renewal. A win-stay rule is very important for exploiting abundant, long-lasting resources. Here, the author tests the use of this rule in wild groups of emperor tamarins (Saguinus imperator imperator), saddle-back tamarins (Saguinus fuscicollis weddelli), and titi monkeys (Callicebus cupreus cupreus) during a series of foraging tasks. Four feeding stations composed of 8 visually similar feeding platforms (2 containing a food reward and 6 containing a sham reward) were constructed. The location of food rewards was reliable during some experiments and unreliable during others. All 3 species consistently adopted a win-stay rule for returning to reward platforms when their location was predictable over time but stopped using it when their spatial distribution changed randomly across experimental trials.