A short study of the foraging behaviour and food resources of migrant waders on an Orkney Island beach

We report a brief, descriptive study of the feeding ecology of waders on Papa Westray island, Orkney, Scotland, in mid-May 2018. We recorded the numbers, distribution and foraging behaviour of birds throughout the tidal cycle in relation to the distribution of seaweed stranded on and growing in an 80-m wide section of sand and boulder beach. We surveyed invertebrates from locations where birds were seen foraging. Supra-littoral, beach-cast seaweed contained a rich invertebrate fauna, which was mostly inaccessible to the waders and only exploited during warm, calm weather when insects and arachnids emerged. More waders foraged on the beach during rising tide than falling tide. The study illustrates the importance of both supra-littoral and intertidal degrading seaweed for sand-dwelling, detritus-feeding invertebrates as the base of a short food-chain supporting migrant waders.