FEY D & LEBRET T (1972) Changes in the avifauna of the Biesbosch in the first year after the elimination of the tide. LIMOSA 45 (3): 101-118.

1. Up to November 1970 the Biesbosch was a fresh water tidal delta area. The rivers Rhine and Meuse are meeting here. The area is situated some 32 km south east of Rotterdam. The tidal amplitudo was some 2 meters. 2. In November 1970 a system of sluices has been put into action and the tidal span has been reduced to some 0.20 m. The high level of the new situation is some 0.60 m below the original high tide level. Some 65 -75% of the former tidal mud flat is permanently water covered now. 3. Changes in the vegetation as well as those in a number of bird species are described. a. Teal Anas crecca numbered some 10.000 - 15.000 birds in former days. Their numbers were greatly reduced immediately after the elimination of the tide. b. The Great Crested Grebe Podieeps eristatus has started to breed in some 10 pairs. c. Spoonbills Platalea leueorodia hold their own in some 70 birds from July to September. d. Coots Fuliea atra increased as breeding birds. They reduced the extension of the reeds, which in the long run may be a positive factor. e. Low nesting species Bluethroat Cyanosylvia sveciea and Bearded Tit Panurus biarmieus have increased in the former tidal reed beds, but in the long run will loose their habitat as the reed beds are permanently dry now and will develop into scrub. Great Crested Grebe Podiceps cristatus Grey Heron Ardea cinerea Purple Heron Ardea purpurea Black-crowned Night Heron Nycticorax nycticorax Eurasian Spoonbill Platalea leucorodia Mallard Anas platyrhynchos Gadwall Anas strepera Common Teal Anas crecca Northern Pintail Anas acuta Garganey Anas querquedula Northern Shoveler Anas clypeata = Spatula clypeata Eurasian Wigeon Anas penelope Common Pochard Aythya ferina Common Shelduck Tadorna tadorna Greylag Goose Anser anser Greater White-fronted Goose Anser albifrons Bewick's Swan Cygnus bewickii Common Buzzard Buteo buteo Osprey Pandion haliaetus Eurasian Coot Fulica atra Eurasian Oystercatcher Haematopus ostralegus Northern Lapwing Vanellus vanellus Little Ringed Plover Charadrius dubius Eurasian Woodcock Scolopax rusticola Pied Avocet Recurvirostra avosetta Great Black-backed Gull Larus marinus Common Wood Pigeon Columba palumbus Great Grey Shrike Lanius excubitor Bluethroat Luscinia svecica = Cyalnosylvia svecica Common Grasshopper Warbler Locustella naevia Great Reed Warbler Acrocephalus arundinaceus Bearded Reedling Panurus biarmicus Eurasian Siskin Carduelis spinus European Goldfinch Carduelis carduelis

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