Migratory geese allow plants to disperse to cooler latitudes across the ocean

Abstract

AbstractAimHow plants can disperse in response to global change is a critical question, yet major knowledge gaps persist about long‐distance dispersal (LDD) mechanisms. We studied the potential a migratory waterfowl has for LDD of flowering plants via gut passage of seeds (endozoochory), comparing spring and autumn migration.LocationUnited Kingdom and Iceland.TaxonPink‐footed Goose (Anser brachyrhynchus, Baillon) and Angiosperma.MethodsWe studied endozoochory by Pink‐footed geese migrating within and between the UK and Iceland by faecal sampling and GPS tracking. We collected 614 faecal samples from 14 areas in the UK and one in Iceland. Using GPS tracks to and from these areas, we estimated how far seeds can be dispersed by Pink‐footed geese, and where to or from.ResultsWe recorded 5507 intact seeds of 35 species (27 terrestrial) from 15 plant families, with lower seed abundance per dropping when birds were migrating northwards in the UK during spring than upon their arrival in autumn. Species richness of plant seeds was highest in Iceland and in autumn. Only four plant species dispersed had an “endozoochory syndrome”. GPS movements showed that seeds retained in guts for up to 24 h can be readily dispersed in both directions between the UK and Iceland, with maximum distances exceeding 2000 km, as well as between UK localities separated by 100 s of km. Movements northwards of ≤400 km were even recorded in autumn. While at stopover sites, daily movements between roost and feeding sites often exceed 20 km.Main ConclusionsPink‐footed geese are LDD vectors for plants previously assumed to lack an LDD mechanism. Spring migration is not the only period when geese move plants to cooler latitudes. The pink‐footed goose can allow terrestrial and aquatic plants to cross the ocean and to keep pace with climate change.