TIMMERMAN A (1960) The Sheld-Duck Tadorna tadorna as a breeding bird in the Netherlands. LIMOSA 33 (3): 159-173.

The bombing on Knechtsand in 1954 and the possibility that the Delta-works. in the South-West of the Netherlands threaten the breeding-grounds of the SheldDucks in this area. led the R.I.V.O.N. (Institute for Nature Conservation Research) to organise a census of the breeding-population of this species in the Netherlands in 1957. The Sheld-Duck breeds on the coasts of Western-Europe. including the British Isles. and locally in the Mediterranean, Black and Caspian Seas. A short description is given of the occurrence of populations in all countries of Western-Europe. The Netherlands are in the centre of the West-European distribution area. An important part of the Sheid-Duck-population of the continent of Europe is breeding in this country. The fairly large numbers of breeding birds are partially due to the complete protection of the species all the year round. A summary of the number of breeding pairs for the periods 1635-1900, 19001945 and 1945-1957 is given. This is based on literature, reports and other information. On table 1 and sketch-map 2 the results of the census of all breeding areas in the Netherlands are given and compared with a census from 1954 (map 1.). The Sheld-Ducks are almost exclUSively breeding in the dunes of the Waddenislands and along the North-sea-coast. Other breeding-places are to be found on the islands in the Delta-area and around the IJsseimeer (former Zuiderzee), Inland breeding is an exception. The total Sheld-Duck breeding-population is estimated at 2500-3300 breedingpairs in 1957. The number of about 3300 non-breeding Sheld-Ducks counted in or near the breeding areas is not considered representative for this group. as many concentrations of non-breeding Sheld-Ducks were not counted. The Sheld-Duck-population of the Netherlands eVidently did not suffer seriously from the bombing at Knechtsand. As the Southern breeding-areas in the Netherlands however will be changed radically by the Delta-plan (building of dams. establishment of industry and increase of tourism) the Sheld-Duck-populations of these areas are endangered. The desirability of creating more nature-reserves is put forward. Common Shelduck Tadorna tadorna

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