High density of white-faced capuchins (Cebus capucinus) and habitat quality in the Taboga Forest of Costa Rica.

Across the globe, primates are threatened by human activities. This is especially true for species found in tropical dry forests, which remain largely unprotected. Our ability to predict primate abundance in the face of human activity depends on different species' sensitivities as well as on the characteristics of the forest itself. We studied plant and primate distribution and abundance in the Taboga Forest, a 516-ha tropical dry forest surrounded by agricultural fields in northwestern Costa Rica. We found that the density of white-faced capuchins (Cebus capucinus) at Taboga is 2-6 times higher than reported for other long-term white-faced capuchin sites. Using plant transects, we also found relatively high species richness, diversity, and equitability compared with other tropical dry forests. Edge transects (i.e., within 100 m from the forest boundary) differed from interior transects in two ways: (a) tree species associated with dry forest succession were well-established in the edge and (b) canopy cover in the edge was maintained year-round, while the interior forest was deciduous. Sighting rates for capuchins were higher near water sources but did not vary between the edge and interior forest. For comparison, we also found the same to be true for the only other primate in the Taboga Forest, mantled howler monkeys (Alouatta palliata). Year-round access to water might explain why some primate species can flourish even alongside anthropogenic disturbance. Forest fragments like Taboga may support high densities of some species because they provide a mosaic of habitats and key resources that buffer adverse ecological conditions.

The nutritional importance of invertebrates to female Cebus capucinus imitator in a highly seasonal tropical dry forest.

OBJECTIVES: Invertebrates are important foods for many primates and provide valuable nutrients often unavailable from plant sources. We examine the diet of white-faced capuchins (Cebus capucinus imitator) to determine: (a) timing and types of invertebrate food consumption; (b) whether invertebrate consumption varies with availability of plant foods; and (c) how invertebrates contribute to energy and protein intake of females during different reproductive states. MATERIALS AND METHODS: We analyze 2 years of behavioral data from 25 adult female capuchins to determine which invertebrates are eaten. We describe annual and monthly invertebrate consumption patterns, and, employing circular statistics, analyze seasonal consumption of the four most important invertebrate groups eaten. We apply logistic regression analyses to tree density and fruit energy data to determine whether capuchin invertebrate foraging is related to fruit energy availability of their most commonly consumed fruits. We evaluate the nutritional contribution of invertebrates to energetic and protein requirements of females over time and across reproductive stages. RESULTS: Capuchins consumed invertebrates from 21 identifiable groups, but their diet was dominated by four orders: Lepidoptera, Orthoptera, Hemiptera, and Hymenoptera. All four orders were consumed in a significantly seasonal pattern, and reduced fruit energy availability was a significant predictor of increased invertebrate foraging. Capuchin females often required invertebrate energy intake to meet their overall monthly energetic needs, particularly while they were lactating, even though they appear to exceed their protein requirements every month. DISCUSSION: These results indicate that invertebrate consumption is critical for capuchin energetic needs, particularly during periods of reduced fruit availability and lactation.

Development of snake-directed antipredator behavior by wild white-faced capuchin monkeys: III. the signaling properties of alarm-call tonality.

In many primates, the acoustic properties of alarm calls can provide information on the level of perceived predatory threat as well as influence the antipredator behavior of nearby conspecifics. The present study examined the harmonics-to-noise ratio (tonality of spectral structure) of alarm calls emitted by white-faced capuchin monkeys (Cebus capucinus) in trees directed at photographic models of a boa constrictor, neotropical rattlesnake, scorpion eater snake, and white snake-shaped control presented on the ground. The average and peak harmonics-to-noise ratios of initial alarm calls by infants, juveniles, and adults and those of nearby second callers were analyzed using PRAAT software. Averaged for age class, the peak harmonics-to-noise ratio of alarm calls directed at the boa constrictor model, characterizing a primary capuchin predator, was reliably higher than the peak harmonics-to-noise ratio of alarm calls directed at the harmless scorpion eater model. This effect was influenced by the higher harmonics-to-noise ratio of infant alarm calls and it disconfirmed our prediction, based on primate vocalization research, that snake perception would increase arousal and alarm-call noisiness. Levels of call tonality did not distinguish the boa and rattlesnake or rattlesnake and scorpion eater models for any age class. Higher alarm-call tonality appeared contagious to nearby perceivers, with focal alarm calling influencing the level of tonality of the first calls of second callers. Together, these findings suggest that the higher peak harmonics-to-noise ratio of capuchin alarm calling directed at snakes is contagious and possibly conveys information about the level of perceived predatory threat.

Anointing with commercial insect repellent by free-ranging Cebus capucinus in Manuel Antonio National Park, Quepos, Costa Rica.

Fur rubbing or anointing is a well known behavior in capuchin monkeys (Cebus and Sapajus), and may have medicinal and/or social functions. Observations of anointing in capuchins have recorded the application of substances derived from both plants (orange, onion, garlic, citronella, and lemongrass) and animals (ants and millipedes). The present study reports on anointing behavior in free-ranging white-headed capuchins, Cebus capucinus, which involved a commercial insect repellent. After looting a bottle of repellent from the bag of a visitor to the Manuel Antonio National Park in Costa Rica, an adult male bit open the bottle and rubbed the leaking liquid over its entire body, focusing mainly on its belly. Other members of the group rubbed themselves against the male's body and were eventually able to retrieve the bottle of repellent and anoint themselves. The repellent is composed mainly of extracts of eucalyptus and citronella. The capuchins may have been attracted by the strong citric scent of the citronella, which is known to stimulate fur-rubbing behavior in these monkeys. This is reinforced by the fact that the sequence of events was quite distinct from that associated with an earlier event, in which a juvenile male looted, tasted, and then discarded a stick of lip gloss and a tube of sunblock. Overall, the observations indicate that the citric scent of the repellent was attractive to the capuchins, especially in comparison with other man-made substances. As the animals partially ingested all the substances, there is clearly a need for more effective regulation of the contact between animals and visitors in the park.