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ABSTRACT
Despite the abundance of migratory geese as herbivores in the Arctic, and ongoing changes in their populations and distributions, little is known about their role in seed dispersal. Climate change requires Arctic plants to adjust their distributions, and avian vectors may have an important role to play. We present the first study of endozoochory (internal transport) of Arctic plants by Canada geese. In central west Greenland, we collected 50 faecal samples, from which we extracted 2943 intact seeds from six species and four families, all but one of which (a non-native species) are extremely common and widespread in this part of Greenland. The majority (95%) of seeds were from Empetrum nigrum, but Carex nardina (3%) and Vaccinium uliginosum (2%) were also abundant. One seed of the non-native Persicaria lapathifolia was recorded. These results suggest migratory geese are likely to be vital vectors of Arctic plants. Although the sample size was small, there were indications that non-breeding geese may disperse more seeds than breeding geese, which stay closer to lakes to reduce the risk of predation, rarely accessing dwarf-scrub heath where non-breeders ingested seeds. Future research should address such possible links between reproductive status and seed dispersal in waterbirds.
KEYWORDS
Branta canadensis; Carex; Empetrum; endozoochory; faeces; seed dispersal
Arctic plant species assemblages are highly structured, on account of sequential Pleistocene glaciations and long-established physical barriers to dispersal and gene flow (such as mountain chains, glaciers and the oceans (Alsos et al. 2015; Eidesen et al. 2013) as well as biotic interactions such as herbivory (Post & Pedersen 2008). Vertebrate seed dispersers are important to maintain and enhance Arctic plant community richness (Bruun et al. 2008). This is especially significant in these times of climate change, which is reducing the extent of sea and terrestrial ice, and affecting seasonality, precipitation and wind patterns. Changing climate and resultant short-term changes in the Arctic environment (for instance, in land ice cover) create new opportunities for colonization of novel plant species and genotypes, as well as imposing different templates for patterns of activity, growth, reproduction and dispersal of existing plant life forms in these regions (Klein et al. 2008). Such vegetation dynamics are dependent on effective dispersal processes, including endozoochory (dispersal of seeds and other diaspores via gut...