HOLTHUIJZEN YA (1979) The food of the Spotted Redshank Tringa erythropus in the Dollard. LIMOSA 52 (1): 22-33.

Spotted Redshank Tringa erythropus The course of numbers of the Spotted Redshank Tringa erythropus in the Dollard shows a peak both in spring and autumn. During spring migration a peak is reached in the first decade of May with numbers up to a maximum of 2200, mainly resting at the German side of the Dollard. The peak in autumn migration occurs in the third decade of August with numbers up to a maximum of 2200 birds, most of them staying on the Dutch part of the area. In the tidal zone Spotted Redshanks feed almost exclusively in small pools and gullies on the mud flats. During ebb-tide the birds feed widely spaced; at high tide they feed tightly-packed in lines along the waterline. Feeding behaviour is characterised by stirring and pecking movements. Analyses of pellets revealed that the food consists of the Shrimp Crangon crangon, Rag Worm Nereis diversicolor, Shore Crab Carcinus maenas and Goby Potamochistus microps. In June and July, the Shrimp and Rag Worm are the main foods whereas in August and September the Rag Worm, Shore Crab and Goby are the most important prey species. In the tidal zone of the Waddenzee two, related species occur: the Redshank Tringa totanus and the Greenshank Tringa nebularia. In the Dollard Redshank and Spotted Redshank differ in feeding behaviour and diet and are therefore ecologically seperated. The Greenshank shows similar feeding behaviour but preys upon larger individuals of the same prey species as the Spotted Redshank. Possibly an ecological seperation is effected by selection on prey size. Greenshanks feed on fine-grained sandy areas in the open Waddenzee whereas the Spotted Redshank favours areas with a relatively high lutumcontent. Because of this these species show a spatial seperation in the tidal zone of the Waddenzee-area.

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