Mechanical and Nutritional Properties of Food as Factors in Platyrrhine Dietary Adaptations

Platyrrhines face a vast array of potential food resources in the Neotropics. Ecological challenges associated with finding, ingesting, masticating, and digesting foods are influenced by food availability and accessibility. Food availability is influenced by seasonal variation in forest productivity, fruiting synchrony, and crop size (e.g., Stevenson 2001; Chapman et al. 2003, but see Milton et al. 2005). Accessibility, on the other hand, is related to such factors as fruit and seed size, the ability to breach mechanically challenging tissues, to tolerate secondary chemical compounds, and to balance nutrient intake. Our goal in this chapter is to examine the diversity of platyrrhine responses to this second variable – gaining access to and processing foods. All platyrrhine genera include fruit in their diets, but the annual percentage of fruit intake ranges widely from 8% in Cebuella to 86% in Ateles (Table 11.1). A wide variety of other resources including exudates, fungi, leaves, flowers, nectar and insect or vertebrate prey make up the balance, or at times the bulk, of annual diets. Some particularly interesting feeding behaviors seen in platyrrhines signal the evolution of specific adaptations. These include the ability to extract and digest plant resources such as gums by Cebuella and Callithrix (Nash 1986; Power and Oftedal 1996), fungi by Callimico (Porter 2001; Porter and Garber 2004; Hanson et al. 2006; Rehg 2006), and seeds by the pitheciins (van Roosmalen et al. 1988; Ayres 1989; Kinzey and Norconk 1990; Kinzey 1992; Peetz 2001; Norconk and Conklin-Brittain 2004). Although gums, seeds and fungi are ingested by other primate species [especially lemurs (Nash 1989; Hemingway 1998) and colobines (Waterman and Kool 1994; Kirkpatrick 1998)], they are used very intensively by these platyrrhines, composing either a majority of their diet during a single season, a subset of the annual diet, or are routinely and extensively used throughout the year.