title: A bird pollinator shows positive frequency dependence and constancy of species choice in natural plant communities.
abstract: Animal pollinators mediate reproduction of many plant species. Foraging theory suggests that animal pollinators exhibit preferences for common plant species in natural communities (positive frequency-dependent foraging) and temporary single-species specialization (flower constancy) during foraging bouts. Positive frequency dependence may favor common plant species; flower constancy may enhance conspecific pollen transfer particularly in rare plant species. Previous experimental studies suggest that avian pollinators are unlikely to exhibit these behaviors. We studied foraging behavior of Cape Sugarbirds (Promerops cafer), the main avian pollinator of many Protea species, using focal-plant and focal-bird sampling, assisted by high-resolution maps of the spatiotemporal distribution of Protea individuals and their flowering status. We found that Sugarbird's visitation preference increased with species' relative floral abundance, and that individual Sugarbirds tended to visit single species in sequence. Flower constancy during foraging bouts was significantly higher than expected from random plant-animal encounters at the scale of pollinator movements. Positive frequency dependence may favor the reproduction of abundant plant species while flower constancy may be particularly important for rare plant species. This first simultaneous study of both behaviors in a natural plant-pollinator system shows that bird pollinators exhibit both types of behavior and, in this way, possibly influence plant community structure.
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.|Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.|Swiss Ornithological Institute, 6204, Sempach, Switzerland.
authors.forename: B
authors.identifier: 0000-0002-7736-7527
authors.initials: B
authors.lastname: Schmid
authors.affiliation: Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.|Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.|Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France.
authors.forename: H
authors.initials: H
authors.lastname: Nottebrock
authors.affiliation: Department of Conservation Biology and Entomology and Centre for Invasion Biology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
authors.forename: K J
authors.initials: KJ
authors.lastname: Esler
authors.affiliation: Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.|Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France.
authors.forename: J
authors.initials: J
authors.lastname: Pagel
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.|Department of Biological Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Straße 9, Frankfurt am Main, 60438, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Böhning-Gaese
authors.affiliation: Institute of Landscape and Plant Ecology, University of Hohenheim, August-von-Hartmann-Street 3, Stuttgart, 70599, Germany.|Institut des Sciences de l'Evolution, UMR 5554, Université Montpellier 2, Place Eugène Bataillon, Montpellier Cedex 05, F-34095, France.
authors.forename: F M
authors.initials: FM
authors.lastname: Schurr
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.|Department of Biological Sciences, Johann Wolfgang Goethe-University, Max-von-Laue-Straße 9, Frankfurt am Main, 60438, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Mueller
authors.affiliation: Senckenberg Biodiversity and Climate Research Centre (BiK-F), Senckenberganlage 25, Frankfurt am Main, 60325, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schleuning
mesh_terms: D000818:Animals; D044822:Biodiversity; D005247:Feeding Behavior; D035264:Flowers; D046109:Passeriformes / Q000502:physiology*; D010944:Plants / Q000145:classification*; D054817:Pollination / Q000502:physiology*; D013045:Species Specificity; D050994:Voltage-Dependent Anion Channels
chemical_list: D050994:Voltage-Dependent Anion Channels
keywords: Cape Floristic Region; Cape Sugarbird; Proteaceae; animal movement; flower constancy; foraging preference; frequency-dependent foraging; pollination; step selection functions