Low Levels of Fruit Nitrogen as Drivers for the Evolution of Madagascar's Primate Communities.

The uneven representation of frugivorous mammals and birds across tropical regions - high in the New World, low in Madagascar and intermediate in Africa and Asia - represents a long-standing enigma in ecology. Several hypotheses have been proposed to explain these differences but the ultimate drivers remain unclear. Here, we tested the hypothesis that fruits in Madagascar contain insufficient nitrogen to meet primate metabolic requirements, thus constraining the evolution of frugivory.

Social and personal information use by squirrel monkeys in assessing predation risk.

The threat of predation can significantly influence prey behaviors through altered perceptions of risk. Prey risk perception is constantly updated via collection of personal and social information about predators. Better understanding of the links between information availability, its use, and prey species' perception of risk will aid in explaining how animals adapt to predation.

Primates in 21st century ecosystems: does primate conservation promote ecosystem conservation?

Contributors to this issue of the American Journal of Primatology were among the participants in an invited symposium at the 2008 Association for Tropical Biology and Conservation meeting in Paramaribo, Suriname. They were asked to assess how essential primates are to tropical ecosystems and, given their research interests, discuss how primate research contributes to the broader understanding about how ecosystems function. This introduction to the issue is divided into three parts: a review of the roles that nonhuman primates play in tropical ecosystems; the implementation of large-scale landscape methods used to identify primate densities; and concerns about the increasingly porous boundaries between humans, nonhuman primates, and pathogens.

The ontogeny of handling hard-to-process food in wild brown capuchins (Cebus apella apella): evidence from foraging on the fruit of Maximiliana maripa.

We examined age-related differences in wild brown capuchins' foraging efficiency and the food-processing behaviors directed toward maripa palm fruit (Maximiliana maripa). A detailed comparison of the different foraging techniques showed that plucking the fruit from the infructescence constituted the main difficulty of this task. Foraging efficiency tended to increase with age, with a threshold at which sufficient strength allowed immatures by the age of three to reach adult-level efficiency.

Development of skilled detection and extraction of embedded prey by wild brown capuchin monkeys (Cebus apella apella).

Brown capuchin monkeys (Cebus apella apella) in Suriname forage on larvae enclosed within healthy bamboo stalks. We applied the searching versus handling dichotomy of optimal foraging models to highlight developmental processes contributing to foraging on embedded prey. Larvae acquisition begins with search; selecting an appropriate stalk and locating the embedded larvae; followed by handling, ripping the stalk open, and extracting the larvae.