Food preferences of Shorelarks Eremophila alpestris, Snow Buntings Plectrophenax nivalis and Twites Carduelis flavirostris wintering in the Wadden Sea

Abstract

Capsule Seeds of plants from lower salt marsh communities are preferred, with insects less important. Methods Droppings of Shorelarks Eremophila alpestris, Snow Buntings Plectrophenax nivalis and Twites Carduelis flavirostris sampled in the German Wadden Sea were analysed and compared with food abundance to assess preferences. Results Shorelarks prefer seeds of Salicornia sp., Suaeda maritima, Atriplex sp., Halimione portulacoides and unidentified small grass seeds. Insects are eaten mainly in periods of seed shortage, but are consumed in smaller amounts during the winter. The food composition of Snow Buntings is very similar, but additionally Triglochin maritimum is commonly eaten. Twites are specialized on seeds of Salicornia sp. and Suaeda maritima and rarely ingest other seeds and insects. All seeds consumed were of plants from lower salt marsh communities. Many halophyte seeds, and especially those that birds feed on, are rich in energy. Large seeds and those which need a long handling time are avoided. Conclusion Changes in the lower salt marshes of the Wadden Sea by embankments and intensified grazing might have been responsible for the rapid population decline from the 1960s to 1980s.