Seasonal variations in numbers of great cormorant (Phalacrocorax carbo) on the Kolut fish farm (nw Serbia)

Seasonal variations in numbers of great cormorant were studied between 1998 and 2004 on ponds of the Kolut fish farm (NW Serbia). Its presence is not detected only during winter. Spring migration culminates in early March. Autumn migration lasts for a long time, with the peak in early October. During the breeding period, the average number never exceeded 20 individuals, probably coming from the nearest breeding colony (35 km from the fishponds). Predation pressure was very low throughout the year, except in October (2.44 individuals/10 ha of ponds). No reason for great cormorant depletion exists in the breeding period, when the predation pressure was below 0.5 birds/10 ha