SEABIRD ECOLOGY IN THE NORTH-SEA

The numbers of all species of seabirds regularly occurring in the North Sea are presented and a brief account is given of the main processes affecting their population dynamics. Monitoring of breeding numbers and known trends, distribution at sea, and the patterns of movement of both breeding and non-breeding birds are described. Feeding methods and foraging behaviour are discussed and methods for determining the diet of seabirds are critically examined. Quantitative methods for determining the amount of food taken, and the ecological energetics of seabirds are dealt with in some detail, including the problem of the availability of food to birds. Physical factors such as tide, weather and sea-state affect several aspects of seabird biology. The relationship between seabird population and fish stocks and fisheries is of increasing importance and the major aspects of these are described and discussed in detail. Other impacts of man such as pollution by oil, chemicals and rubbish are also important. Predation by introduced mammals and also by the native larger gulls, and unintentional disturbance resulting from human recreation, can have serious effects on breeding colonies. In the south-eastern North Sea low-lying coasts are vulnerable to flooding and affected by land reclamation and coastal management.