title: Bearded saki feeding strategies on an island in Lago Guri, Venezuela.
abstract: Free-ranging bearded sakis (Chiropotes spp.) live in relatively large social groups (22-65+), inhabit very large home ranges (200-1,000 ha), and travel long distances (1.8 to >7 km) each day. While these characteristics would seem to reduce their ability to occupy habitat fragments, several studies suggest otherwise. The key to their success may lie in their dietary adaptations. Bearded sakis are strongly frugivorous, but are primarily seed eaters, and are able to ingest both young and mature fruit. We examined feeding activities of a group of bearded sakis over a 19-month period on a 180 ha island in Lago Guri, Venezuela. Given their feeding adaptations, we predicted that they would minimize peaks and troughs in plant species used for food, limit seasonal variation in the mechanical properties of foods ingested, and balance ingestion of energy-rich foods (e.g. lipids, nonstructural carbohydrates (TNC), and/or free simple sugars). We found that bearded sakis on Danto Manchado had a diverse (plant-based) diet, but two resources (Pradosia caracasana, Sapotaceae, and Oryctanthus alveolatus, Loranthaceae) provided a stable dietary base and were present in the diet almost every month. Second, we found little variation in the mechanical-resistance properties of fruits opened seasonally. Third, they alternated months ingesting foods with high TNC content and months of high lipid content. This may be an attempt to balance energy intake from available foods. Finally, their social propensity to split up into subgroups may predispose them to reduce group sizes to accommodate smaller available areas. We suggest that bearded sakis use both ecological and behavioral mechanisms to survive in smaller-than-typical areas. Longer-term studies (beyond a few generations) of bearded sakis in habitat fragments would allow us to estimate minimum survival area and identify critical resources or resource combinations.
authors: Department of Anthropology and School of Biomedical Sciences, Kent State University, Kent, Ohio.
authors: Marilyn A
authors: MA
authors: Norconk
authors: Department of Human Evolutionary Biology, Peabody Museum, Harvard University, Cambridge, Massachusetts.
authors: Nancy L
authors: NL
authors: Conklin-Brittain
mesh_terms: D000818:Animals; D004032:Diet / Q000662:veterinary*; D004040:Dietary Carbohydrates; D017753:Ecosystem; D005247:Feeding Behavior; D005260:Female; D005638:Fruit / Q000737:chemistry; D060434:Herbivory; D008055:Lipids; D008297:Male; D055595:Mechanical Phenomena; D053820:Pitheciidae / Q000502:physiology*; D012621:Seasons; D012919:Social Behavior; D014687:Venezuela
chemical_list: D004040:Dietary Carbohydrates; D008055:Lipids
keywords: Neotropics; Pitheciidae; habitat fragment; nutrition; platyrrhine; seed eating