Picking pithy plants: Pith selectivity by wild white-faced capuchin monkeys, Cebus imitator
Understanding why primates choose certain fallback foods can illuminate nutritional ecology and behavioral adaptation. Over 3.5 years, researchers studied plant‑pith foraging by white‑faced capuchins (Cebus imitator) in a tropical dry forest. Capuchins consumed pith from only 11 of ~300 available species, most often Bursera simaruba. Pith foraging was not tied to fruit scarcity but peaked during seasonal transitions. Compared with avoided species, dietary pith plants offered greater pith quantity, softer tissues and richer terpenoid profiles—bioactive compounds with known medicinal properties. These findings suggest that pith selectivity is shaped by mechanical ease, chemical cues and potential zoopharmacognosy, highlighting how climatic seasonality influences primate feeding behavior.
Subject Tags
- Forest
- Life Sciences
- Wildlife
Abstract
Understanding diet selectivity is a longstanding goal in primate ecology. Deciphering when and why primates consume different resources can provide insights into their nutritional ecology as well as adaptations to food scarcity. Plant pith, the spongy interior of plant stems, is occasionally eaten by primates, but the context is poorly understood. We examine the ecological, mechanical, chemical, and nutritional basis of plant pith selection by a wild, frugivorous-omnivorous primate (Cebus imitator). We test the hypothesis that pith is a fallback food, that is, consumed when fruit is less abundant, and test for differences between plant species from which pith is eaten versus avoided. We collected 3.5 years of capuchin pith consumption data to document dietary species and analyzed “pith patch visits” in relation to fruit availability, visits to fruit patches and climatic seasonality. We analyzed dietary and non-dietary species for relative pith quantity, mechanical hardness, odor composition and macronutrient concentrations. Capuchins ate pith from 11 of ~300 plant species common in the dry forest, most commonly Bursera simaruba. We find that pith consumption is not directly related to fruit availability or fruit foraging but occurs most frequently (84% of patch visits) during the months of seasonal transition. Relative to common non-dietary species, dietary pith species have relatively higher pith quantity, have softer outer branches and pith, and contain more terpenoids, a class of bioactive compounds notable for their widespread medicinal properties. Our results suggest that greater pith quantity, lower hardness, and a more complex, terpenoid-rich odor profile contribute to species selectivity; further, as pith is likely to be consistently available throughout the year, the seasonality of pith foraging may point to zoopharmacognosy, as seasonal transitions typically introduce new parasites or pathogens. Our study furthers our understanding of how climatic seasonality impacts primate behavior and sheds new light on food choice by an omnivorous primate.
Citation
DePasquale, A. N., Poirier, A. C., Mah, M. A., Villalobos Suarez, C., Guadamuz, A., Cheves Hernandez, S., ... & Melin, A. D. (2025). Picking pithy plants: Pith selectivity by wild white‐faced capuchin monkeys, Cebus imitator. American Journal of Primatology, 87(1), e23549. https://doi.org/10.1002/ajp.23549
TNC Authors
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Jeremy D. Hogan
The Nature Conservancy