Fruit and leaf selection based on plant species and maturity in black-handed spider monkeys (Ateles geoffroyi)

Food selection in primates is guided by a sensory evaluation of the physical and chemical properties of the foods. These properties vary with plant species, plant part, and plant maturity. Spider monkeys generally consume ripe fruits, but their diet also includes unripe fruits and young and mature leaves from a wide variety of plant species. We evaluated food selection in ten adult black-handed spider monkeys (Ateles geoffroyi) living in a controlled environment in Catemaco (Veracruz, Mexico). We used six plant species which are part of their natural diet and compared selection between ripe and unripe fruits and young and mature leaves, respectively, for the same plant species. We also analyzed the sucrose content, pH, size, and color of fruits and the color and size of leaves of each plant species. For fruit selection, our model showed that 75% of choices depended on an association between the plant species and the stage of maturity. In contrast, our model predicted 52% of the leaf selection, and monkeys considered both the stage of maturity and the plant species. Our results suggest that Ateles geoffroyi exhibit a more specific food selection for fruits than leaves, resulting in different food choices based on the physical and chemical properties of these food items.