SAEIJS HLF & BAPTIST HJM (1978) Waders in the Dutch Delta area. LIMOSA 51 (1): 52-63.

The numbers of waders counted during the simultaneous counts in the Delta area of the south-west of the Netherlands in 1966-67 and 1974-75 are being compared. In 1969-71 some major closures of dikes were completed. As a result of this the tide (almost) disappeared in the Haringvliet and in the Grevelingen. The number of waders counted in these two areas was about 40,000 lower after the closures. The number of waders counted in the whole Delta area was equal or even higher. On the remaining tidal areas the results of the counts differ per species from each other to a great extent, sometimes it does even differ for one species in several areas. By means of a method of evaluation we have tried to indicate the changes in ornithological value of the Delta area for waders. In the discussion the reliability of birdcounts and their evaluation is exposed. A number of questions arose about the causes and effects of the changes in numbers. Moreover it is noted that after 1985 the intertidal area in the Delta area will decrease again.

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