LEOPOLD MF, BAPTIST HJB, WOLF P & OFRINGA HR (1995) Common Scoters Melanitta nigra in The Netherlands. LIMOSA 68 (2): 49-64.

Black Scoter Melanitta nigra The Common Scoter has long been known as a common migrant and winter visitor along the Dutch coast. Good estimates of numbers staging in Dutch waters were lacking however, due to the elusive habits of the species. From incidental records gleaned from literature, its status in the past was reconstructed. At the turn of the century the species was a very common bird along the coast, but quantitative data are lacking. In the first half of this century groups of tens of thousands of birds were seen migrating or swimming on several occasions, and the species commonly washed up as oil-victim, indicating common and widespread occurrence in coastal waters. In the 1960's the first aerial and ship surveys were carried out in the Wadden Sea area. These indicated that some 40 000 Common Scoters wintered in the western Wadden Sea. Moreover, there were several sightings of large (>10 000) groups in the adjacent North Sea. In the 1970's, surveys in the Wadden Sea showed that numbers of wintering scoters had declined to a maximum of 8000. In the Delta area, where numbers of ducks were monitored by plane from 1975 onward, some 15-25 000 birds wintered in the 1970's and early 1980's. In those years there were few surveys along the coasts of the Dutch mainland and the Frisian Islands and most information comes from seawatching sites. Records of groups of 5000 or more were rare, and only in 1978 around 10 000 were recorded at one site (Tab. 1 and 2). From 1985 onward, the whole Dutch coast was surveyed by plane, and shipboard surveys were carried out in 1989-93. In the Delta area, large numbers (c. 20 000) returned in the winters of 1986-88 after a low in the early 1980's (Fig. 1), but numbers declined again after a large land reclamation project was carried out in the ducks' favourite area. Off mainland Holland numbers were generally low, but in the winter of 1986/87 about 60 000 Common Scoters were found wintering here. The coastal waters north of the Frisian Islands became the most important area in the early 1990's (Fig. 2). In 1989/90 c. 10 000 Common Scoters wintered near Schiermonnikoog, and in the winters of 1990-93, 100135 000 wintered in this area, at first off Schiermonnikoog and later off Terschelling. Numbers that remain in Dutch waters in summer are less well documented. After an old record (1888) of uncountable numbers moulting in the Wadden Sea near Schiermonnikoog, moulting birds were not seen in any numbers for over 100 years. In the 1970's moulted feathers were found in considerable numbers at Schiermonnikoog, but moulting ducks were not seen. Only in 1991 groups of moulting Common Scoters were found: 550 in the Delta area and c. 11 000 and 250 in the North Sea off Terschelling and Rottum, respectively. Therefore, Common Scoters should be considered as (moulting) summering birds in rather large numbers in The Netherlands, at least in some years. A rich supply of the clam Spisula subtruncata was present at all locations where the scoters wintered in large numbers since 1987, and this bivalve is now the most important food items for the ducks. From 1992 to 1994 this food source also attracted Dutch shellfishermen. Their activities disturbed the ducks and drove them away from their favourite site off Terschelling. This branch of fishery is ill-regulated, and it seems capable of destroying the ducks' feeding grounds. A set of regulations, by which shellfishery in the areas where the ducks winter in a given year is closed, is recommended. Other improvements of the management of seaducks in The Netherlands would include specific vigilance for oil pollution in areas with concentrations of seaducks.

[free pdf] [dutch summary]