title: Cheating on the mutualistic contract: nutritional gain through seed predation in the frugivorous bat Chiroderma villosum (Phyllostomidae).
abstract: Most frugivorous bats are efficient seed dispersers, as they typically do not damage seeds and transport them over long distances. In contrast, bats of the phyllostomid genus Chiroderma cheat fig trees by acting more as seed predators than as seed dispersers. The bats initially separate seeds from fruit pulp in the mouth. After extracting the juice from the fruit pulp, they thoroughly chew the seeds and spit out small seed fragments in a pellet. Consequently, the faeces contain almost no viable seeds. We compared the nutrient content of intact fig seeds with ejecta and faecal samples from both Chiroderma villosum and the 'conventional' frugivorous bat Artibeus watsoni. We show that C. villosum can extract nutrients from the seeds, especially protein and fat. The processing time of figs showed no significant difference between the two bat species. Food-choice experiments showed that C. villosum preferred fig species with more seeds over those with fewer seeds. This preference, in combination with the specialized seed-chewing behaviour, leads to an increased nutrient intake per fig. This unique strategy enables C. villosum to satisfy its nutritional requirements with a lower number of figs than other species, which decreases the amount of energy necessary for foraging flights as well as the predation risk during foraging.
authors.affiliation: University of Ulm, Institute of Evolutionary Ecology and Conservation Genomics, Albert-Einstein-Allee 11, Ulm D-89069, Germany insa.wagner@uni-ulm.de.
authors.forename: Insa
authors.initials: I
authors.lastname: Wagner
authors.affiliation: University of Hamburg, Animal Ecology and Conservation, Hamburg, Germany.
authors.forename: Jörg U
authors.initials: JU
authors.lastname: Ganzhorn
authors.affiliation: University of Ulm, Institute of Evolutionary Ecology and Conservation Genomics, Albert-Einstein-Allee 11, Ulm D-89069, Germany Smithsonian Tropical Research Institute, Balboa, Panama.
authors.forename: Elisabeth K V
authors.initials: EK
authors.lastname: Kalko
authors.affiliation: University of Ulm, Institute of Evolutionary Ecology and Conservation Genomics, Albert-Einstein-Allee 11, Ulm D-89069, Germany Smithsonian Tropical Research Institute, Balboa, Panama.
authors.forename: Marco
authors.initials: M
authors.lastname: Tschapka
mesh_terms: D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D004435:Eating / Q000502:physiology; D005247:Feeding Behavior; D030681:Ficus / Q000737:chemistry*; D005518:Food Preferences; D005638:Fruit; D058614:Seed Dispersal; D012639:Seeds / Q000737:chemistry; D013559:Symbiosis
keywords: Feeding behaviour; Fig-eating bat; Mutualism; Nutrient; Parasite