Abstract

Knowledge of feeding behaviour of non-breeding Sanderlings is very scarce for South Pacific populations. We report data on diet and prey selection by Sanderlings wintering in Isla Guamblin National Park in the Chilean fjords. We sampled macroinvertebrates, collected feces from monospecific roosting sites, and collected bivalves for inspection of their siphons. Although the amphipod Orchestoidea tuberculata was most abundant, main prey items for Sanderlings were the coleopteran Phalerisida maculata and surf clams (Mesodesma donacium) siphons. Of the surf clams collected, 44.7% (n=85) one or both siphons had been eaten by Sanderlings. Sanderlings predated on siphons of surf clams above 2 cm, suggesting that smaller surf clams are not a profitable prey for this species. Our results confirm the importance of combining methods for studies of diet and prey selection and reveal the importance of collecting bivalves for inspection of their siphons when prey identification in the field is difficult. Accepted 23 April 2009. © The Neotropical Ornithological Society.