Picking pithy plants: Pith selectivity by wild white-faced capuchin monkeys, Cebus imitator

Area of Science:

• Primate Ecology and Behavior
• Nutritional Ecology
• Plant-Animal Interactions

Background:

• Understanding primate diet selectivity is crucial for nutritional ecology and adaptations to food scarcity.
• Plant pith consumption by primates is poorly understood, with its role as a fallback food needing investigation.

Purpose of the Study:

• To examine the ecological, mechanical, chemical, and nutritional factors influencing plant pith selection by wild capuchin monkeys (Cebus imitator).
• To test the hypothesis that pith serves as a fallback food and to identify differences between pith-eating and non-pith-eating plant species.

Main Methods:

• Collected 3.5 years of capuchin pith consumption data, analyzing pith patch visits in relation to fruit availability, fruit foraging, and climatic seasonality.
• Analyzed dietary and non-dietary plant species for pith quantity, mechanical hardness, odor composition, and macronutrient concentrations.

Main Results:

• Capuchins consumed pith from 11 out of ~300 common plant species, with Bursera simaruba being the most frequent source.
• Pith consumption was not directly linked to fruit availability but occurred most frequently during seasonal transitions (84% of visits).
• Dietary pith species exhibited higher pith quantity, softer branches and pith, and a more complex, terpenoid-rich odor profile compared to non-dietary species.

Conclusions:

• Plant pith selection by capuchins is influenced by greater pith quantity, lower hardness, and specific olfactory cues (terpenoids).
• The seasonal pattern of pith foraging, despite consistent availability, suggests potential zoopharmacognosy, possibly for combating seasonal parasites or pathogens.
• This study enhances understanding of how climatic seasonality impacts primate behavior and food choices in omnivorous primates.