LOK CM & BAKKER L (1988) Seasonal use of feeding grounds by Cormorants Phalacrocorax carbo at Voorne. LIMOSA 61 (1): 7-12.

Great Cormorant Phalacrocorax carbo In 1984 Cormorants started to breed at Brede Water, a dune lake in the northern Delta area. The colony increased from 26 nests in the first year to 900 nests in 1987. Although the birds nest in a well protected reserve, they still may be vulnerable, because of their tendency to fish in the Europoort harbours and other areas with a risk of pollution. Therefore, a more detailed investigation into the use of feeding grounds was initiated. The results show that in winter mainly rivers and harbours with freshwater are visited, but in the breeding season the birds prefer to fish at sea. In addition, the salt water lake Grevelingen is used as a feeding area for a short period in spring. Lakes with many recreational activities are clearly avoided. The observed selection pattern shows that, at least during the reproduction period, feeding grounds with relatively clean water are visited. Breeding success is high with 2.4-2.6 fledged nestlings per successful nest. It is postulated that the strong preference for the sea in the breeding season and the high reproduction rate are related to the abundant occurrence of herring and sprat at Voorne's coast in that period

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