Breeding performance in Great Cormorants:Factors of importance for spatiotemporal variation in Danish waters

Breeding success is a key demographic parameter. Information about this parameter can help us when we try to understand why populations develop as they do. For Denmark we wonder why trends differ among regions and why the breeding population has remained stable at the national level and with far fewer breeding pairs than 20-30 years ago (Fig. 1). Could it be that far fewer fish are available for the Cormorants nowadays so that each breeding pair now produce only a few young? We here present a few examples of variation among colonies and changes over the years.