title: Behavioral and physiological responses to fruit availability of spider monkeys ranging in a small forest fragment.
abstract: Numerous animal species currently experience habitat loss and fragmentation. This might result in behavioral and dietary adjustments, especially because fruit availability is frequently reduced in fragments. Food scarcity can result in elevated physiological stress levels, and chronic stress often has detrimental effects on individuals. Some animal species exhibit a high degree of fission-fusion dynamics, and theory predicts that these species reduce intragroup feeding competition by modifying their subgroup size according to resource availability. Until now, however, there have been few studies on how species with such fission-fission dynamics adjust their grouping patterns and social behavior in small fragments or on how food availability influences their stress levels. We collected data on fruit availability, feeding behavior, stress hormone levels (measured through fecal glucocorticoid metabolites (FGCM)), subgroup size, and aggression for two groups of brown spider monkeys (Ateles hybridus) in a small forest fragment in Colombia and examined whether fruit availability influences these variables. Contrary to our predictions, spider monkeys ranged in smaller subgroups, had higher FGCM levels and higher aggression rates when fruit availability was high compared to when it was low. The atypical grouping pattern of the study groups seems to be less effective at mitigating contest competition over food resources than more typical fission-fusion patterns. Overall, our findings illustrate that the relationship between resource availability, grouping patterns, aggression rates, and stress levels can be more complex than assumed thus far. Additional studies are needed to investigate the long-term consequences on the health and persistence of spider monkeys in fragmented habitats.
authors.affiliation: Behavioral Ecology and Sociobiology Unit, German Primate Center, Göttingen, Germany; Fundación Proyecto Primates, Bogotá, Colombia.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Rimbach
authors.forename: Andrés
authors.initials: A
authors.lastname: Link
authors.forename: Andrés
authors.initials: A
authors.lastname: Montes-Rojas
authors.forename: Anthony
authors.initials: A
authors.lastname: Di Fiore
authors.forename: Michael
authors.initials: M
authors.lastname: Heistermann
authors.forename: Eckhard W
authors.initials: EW
authors.lastname: Heymann
mesh_terms: D000374:Aggression; D000818:Animals; D053819:Atelinae / Q000502:physiology* / Q000523:psychology*; D001522:Behavior, Animal / Q000502:physiology; D003105:Colombia; D004032:Diet; D017753:Ecosystem; D005243:Feces / Q000737:chemistry; D005247:Feeding Behavior; D005260:Female; D005523:Food Supply; D065928:Forests; D005638:Fruit; D005938:Glucocorticoids / Q000032:analysis; D008297:Male; D012919:Social Behavior; D013312:Stress, Physiological
chemical_list: D005938:Glucocorticoids
keywords: aggression; fission-fusion dynamics; glucocorticoid metabolites; habitat fragmentation; spider monkeys