LEBRET T & MULLIE WC (1975) The Bewicks Swan Cygnus bewickii on Walcheren and elsewhere in Zeeland, in the Netherlands. LIMOSA 48 (1): 40-59.

Bewick's Swan Cygnus bewickii 1. This paper deals with the recent increas.? of the Bewick's Swan on the isles of Walcheren and Schouwen-Duiveland, Zeeland province, the Netherlands. Before the series of severe winters of 1939-40 to 1946-47 the Bewick's Swans were very rare in the area. In the years 1947-1955 some 10 to 30 may have been present. There is a distinct increase going on since 1965. 2. The seasonal distribution of the Bewick's Swans from 1970-71 to 1973-74 is shown in Fig. 3. There appear to be two peaks, one early in winter, the second in FebruaryMarch. The decrease between these peaks may be due to emigration towards British winter quarters. The second peak may be partly due to spring migration of British winter birds. 3. In Table 1 the seasonal distribution in the various parts of Zeeland province are shown. Schouwen-Duiveland, which has the second greatest sub-population, is evacuated at the end of January. Hence part of the February-March peak on Walcheren may be due to birds from Schouwen-Duiveland. 4. The number of Bewick's Swans shown in Fig. 3 may be used as a basis for the calculation of the swan-days spent on Walcheren. In 1971-72, 1972-73 and 1973-74 the area has been used during ca. 14,000, 23,000 and 45,000 swan-days resp. This is a much greater increase than is suggested by the annual maxima shown in Fig. 2. 5. Some observations of Bewick's Swans migrating over Walcheren are described. 6. Sight records of 7 ringed Bewick's Swans are described. 3 birds were seen in two subsequent winters. The longest stay stated was 119 days. 7. Both the feeding habitats and the roosts are described. The general position in the SW of the Netherlands seems favourable. Mean temperatures of December-February on Walcheren and Schouwen are 3.4 0 C as to 2.2 0 C for the centre of the Netherlands. The Bewicks on Walcheren are grazing on pasture land, which is slightly uneven due to former tidal influences and to mediaeval peat digging. The birds prefer fields with extensive standing water and those adjoining main ditches of some 10-15 m wide. They roost mostly on shallows in the former estuary Veerse Meer. Distances covered on dusk and dawn flight are 9-10 km and sometimes up to 15-16 km. There is an increasing tendency to roost on main ditches and standing waters. 8. The future of the Bewick's Swans in the area described is discussed. The Walcheren pastures might provide food to more swans than there were in 1973-74, but the swans beginning to eat potatoes in december 1973 suggests that the limit might soon be reached. The construction of a high-way from the Oosterschelde across Walcheren would destroy several favorite feeding grounds.

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