Picking pithy plants: Pith selectivity by wild white‐faced capuchin monkeys, <i>Cebus imitator</i>

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 composi- tion, 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