title: Overseas seed dispersal by migratory birds.
abstract: Long-distance dispersal (LDD) promotes the colonization of isolated and remote habitats, and thus it has been proposed as a mechanism for explaining the distributions of many species. Birds are key LDD vectors for many sessile organisms such as plants, yet LDD beyond local and regional scales has never been directly observed nor quantified. By sampling birds caught while in migratory flight by GPS-tracked wild falcons, we show that migratory birds transport seeds over hundreds of kilometres and mediate dispersal from mainland to oceanic islands. Up to 1.2% of birds that reached a small island of the Canary Archipelago (Alegranza) during their migration from Europe to Sub-Saharan Africa carried seeds in their guts. The billions of birds making seasonal migrations each year may then transport millions of seeds. None of the plant species transported by the birds occurs in Alegranza and most do not occur on nearby Canary Islands, providing a direct example of the importance of environmental filters in hampering successful colonization by immigrant species. The constant propagule pressure generated by these LDD events might, nevertheless, explain the colonization of some islands. Hence, migratory birds can mediate rapid range expansion or shifts of many plant taxa and determine their distribution.
authors.affiliation: Estación Biológica de Doñana, CSIC, C/ Américo Vespucio, s/n, Sevilla 41092, Spain dviana@ebd.csic.es.
authors.forename: Duarte S
authors.identifier: http://orcid.org/0000-0002-7864-0871
authors.initials: DS
authors.lastname: Viana
authors.affiliation: Estación Biológica de Doñana, CSIC, C/ Américo Vespucio, s/n, Sevilla 41092, Spain.
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0002-6205-6769
authors.initials: L
authors.lastname: Gangoso
authors.affiliation: Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Sciencepark 904, 1098 XH Amsterdam, The Netherlands.
authors.forename: Willem
authors.identifier: http://orcid.org/0000-0002-5250-8872
authors.initials: W
authors.lastname: Bouten
authors.affiliation: Estación Biológica de Doñana, CSIC, C/ Américo Vespucio, s/n, Sevilla 41092, Spain.
authors.forename: Jordi
authors.identifier: http://orcid.org/0000-0002-4664-9011
authors.initials: J
authors.lastname: Figuerola
mesh_terms: D017954:Africa South of the Sahara; D025041:Animal Migration; D000818:Animals; D001717:Birds / Q000502:physiology*; D058893:DNA Barcoding, Taxonomic; D018744:DNA, Plant / Q000737:chemistry; D005060:Europe; D040362:Geographic Information Systems; D058865:Introduced Species; D009792:Oceans and Seas; D058614:Seed Dispersal; D012639:Seeds / Q000235:genetics; D013030:Spain
chemical_list: D018744:DNA, Plant
keywords: biogeography; endozoochory; long-distance dispersal; migratory birds; seed dispersal