title: The Influence of Seasonal Frugivory on Nutrient and Energy Intake in Wild Western Gorillas.
abstract: The daily energy requirements of animals are determined by a combination of physical and physiological factors, but food availability may challenge the capacity to meet nutritional needs. Western gorillas (Gorilla gorilla) are an interesting model for investigating this topic because they are folivore-frugivores that adjust their diet and activities to seasonal variation in fruit availability. Observations of one habituated group of western gorillas in Bai-Hokou, Central African Republic (December 2004-December 2005) were used to examine seasonal variation in diet quality and nutritional intake. We tested if during the high fruit season the food consumed by western gorillas was higher in quality (higher in energy, sugar, fat but lower in fibre and antifeedants) than during the low fruit season. Food consumed during the high fruit season was higher in digestible energy, but not any other macronutrients. Second, we investigated whether the gorillas increased their daily intake of carbohydrates, metabolizable energy (KCal/g OM), or other nutrients during the high fruit season. Intake of dry matter, fibers, fat, protein and the majority of minerals and phenols decreased with increased frugivory and there was some indication of seasonal variation in intake of energy (KCal/g OM), tannins, protein/fiber ratio, and iron. Intake of non-structural carbohydrates and sugars was not influenced by fruit availability. Gorillas are probably able to extract large quantities of energy via fermentation since they rely on proteinaceous leaves during the low fruit season. Macronutrients and micronutrients, but not digestible energy, may be limited for them during times of low fruit availability because they are hind-gut fermenters. We discuss the advantages of seasonal frugivores having large dietary breath and flexibility, significant characteristics to consider in the conservation strategies of endangered species.
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, D-04103, Leipzig, Germany; Department of Animal and Human Biology, University of Rome "La Sapienza", 00185, Rome, Italy.
authors.forename: Shelly
authors.initials: S
authors.lastname: Masi
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, D-04103, Leipzig, Germany.
authors.forename: Roger
authors.initials: R
authors.lastname: Mundry
authors.affiliation: RG Evolutionary Ecology, Leibniz-Institute for Zoo and Wildlife Research, D-10315, Berlin, Germany.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Ortmann
authors.affiliation: WCS Nyungwe Project, WSC Rwanda Program, Kigali, Rwanda.
authors.forename: Chloé
authors.initials: C
authors.lastname: Cipolletta
authors.affiliation: Department of Animal and Human Biology, University of Rome "La Sapienza", 00185, Rome, Italy.
authors.forename: Luigi
authors.initials: L
authors.lastname: Boitani
authors.affiliation: Max Planck Institute for Evolutionary Anthropology, D-04103, Leipzig, Germany.
authors.forename: Martha M
authors.initials: MM
authors.lastname: Robbins
mesh_terms: D000818:Animals; D000835:Animals, Wild / Q000502:physiology*; D018533:Biomass; D004032:Diet; D002149:Energy Intake / Q000502:physiology*; D005260:Female; D005502:Food; D005638:Fruit / Q000502:physiology*; D006071:Gorilla gorilla / Q000502:physiology*; D060434:Herbivory / Q000502:physiology*; D016014:Linear Models; D008297:Male; D025341:Principal Component Analysis; D012621:Seasons