EERDEN MR VAN, PROP J & VEENSTRA K (1979) The development of the. breeding populations in several species of birds in the Lauwerszee area in eight years following reclamation. LIMOSA 52 (3): 176-190.

This paper deals with the development of breeding populations in several species of birds in the Lauwerszee-area in eight years following reclamation in 1969. Plant colonization on the sandflats started from the bordering saltings and consisted mainly of saline species such as Glasswort Sa/icornia spp. Because of a very slow progress in desalination even after eight years the vegetation clearly shows aspects of a saltmarsh community. Two groups of species can be detected according to their pattern of colonization ofthe sandflats. ,- I. Primary species colonizing the new space within one or two years after embankment. Avocet Recurvirostra avosetta, Black-Headed Gull Larus ridibundus and Common Tern Sterna hirundo showed a shift in breeding site from the edges to the centre of the area. Other pioneers belonging to this group such as Kentish Plover Charadrius a/exandrinus and Little Tern Sterna a/bit rons moved in from abroad as they were not breeding in the estuarine situation before 1969. Many species of this group breed in colonies, often on bare ground. The most numerous of them, the Black-Headed Gull with about 10.000 breeding pairs is feeding mainly outside the breeding habitat (agricultural areas). Others as Avocet feed close to their nests on midge larvae Chironomidae and small Worms Tubificidae which they catch in the fresh water mud along the creeks. 2. Secondary species following the development in vegetation structure. In this group clear examples could be shown in Lapwing Vanellus vanellus, Black-Tailed Godwit Limosa limosa and Ruff Philomachus pugnax. The development of natural meadows both means the creation of suitable breeding habitat and an increment of food supply. Lapwings are to a large extent dependent on small insects and spiders which they prey upon the vegetation. Others such as the Black-Tailed Godwit use the vegetation mainly as cover while breeding and feed on the infauna of the fresh water mud. The macro benthos of the sandflats is still very poor. It is argued that nowadays the colonizing capacity of primary species such as Kentish Plover and Little Tern might be lowered. Though suitable breeding habitat was abundant in the first years the observed numbers of these species were comparatively low.. ##### Mallard Anas platyrhynchos Gadwall Anas strepera Northern Shoveler Anas clypeata = Spatula clypeata Tufted Duck Aythya fuligula Common Shelduck Tadorna tadorna Western Marsh Harrier Circus aeruginosus Common Kestrel Falco tinnunculus Grey Partridge Perdix perdix Common Pheasant Phasianus colchicus Common Moorhen Gallinula chloropus Eurasian Coot Fulica atra Eurasian Oystercatcher Haematopus ostralegus Common Ringed Plover Charadrius hiaticula Little Ringed Plover Charadrius dubius Kentish Plover Charadrius alexandrinus Northern Lapwing Vanellus vanellus Ruff Philomachus pugnax Common Redshank Tringa totanus Black-tailed Godwit Limosa limosa Pied Avocet Recurvirostra avosetta Little Gull Hydrocoloeus minutus = Larus minutus Black-headed Gull Chroicocephalus ridibundus = Larus ridibundus Common Tern Sterna hirundo Little Tern Sternula albifrons = Sterna albifrons Short-eared Owl Asio flammeus

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