ABSTRACT
Two platyrrhine families and six genera were covered in this chapter: the howlers and spider monkeys of the atelids, and the seed predators and titis of the pitheciids. The descriptions of primate behavior are arranged under four headings: ecology, sociality, life cycle, and cognition. Howlers take their name from their unusual distance call. They are distinctively folivorous among the platyrrhines and their behavior is strongly affected by energy conservation. Spider monkeys are the most widespread genus, ranging from southern Mexico to northern Bolivia. Males and females are virtually identical in size, color, and slender physique. Spider monkeys are frugivorous and live in male-philopatric fission-fusion communities that parallel chimpanzees in several ways. Pitheciid seed predators have distinctive diets based on their ability to crack open hard-shelled seeds and fruits with their procumbent incisors. Their social systems vary across the taxa from pair-groups to large troops. Titis are small frugivores characterized by knit pair-groups in which paired adults display strongly affiliative behaviors.
