From August 1988 onwards a new moulting area for Shelducks was established in the western Dutch Wadden Sea off the former island of Wieringen. A maximum of 1000 birds moulted here that year, while in previous years late summer numbers barely exceeded some 40 individuals. The next year the number of moulting birds had already increased to 5000. A more extensive survey in 1991 showed that 9000-10,000 Shelducks passed their wing-moult here, while elsewhere in the Dutch Wadden Sea, near the islands of Terse helling and Ameland a further 10,000 birds were found moulting. The importance and significance of this new moulting site is briefly discussed in a broader context.