TIME BUDGETS OF MIGRATING WADERS IN THE WADDEN SEA - RESULTS OF THE INTERDISCIPLINARY PROJECT ECOSYSTEM RESEARCH LOWER SAXONIAN WADDEN SEA

The Wadden Sea is an important refuelling station for a large number o f arctic and subarctic birds. Each spring and autumn they use the Wadd en Sea as a staging area to accumulate energy for their long flights t o the breeding and wintering grounds, respectively. In 1992 the interd isciplinary project Ecosystem Research Lower Saxonian Wadden Sea was s tarted. The main study area is the intertidal zone between the island of Spiekeroog and the mainland. The aim of the pilot study in 1992 was to explore the importance of this area for birds. Preliminary investi gations of the activity patterns and time budgets of five common wader s were carried out. Time budgets provide multiple insights into the ov erall relation and adaptation of a species to its environment. The res ults show that the area is a very important staging site for waders an d waterfowl. In total 77 species were recorded. Waders were the domina nt group throughout the year. A high number of birds used the islands as roosting sites. For feeding they preferred the mudflats near the ma inland coast. The behaviour of all investigated species was largely de termined by the tidal rhythm. Foraging lasted from 3-5 hours before lo w tide to 3-4 hours after. In spring birds spent between one and three hours longer foraging than in autumn.