Changes in the wintering diet of great cormorant Phalacrocorax carbo (1994-2004) in Navarra (northern Spain):: Effects of the reintroduction of aloctone ictiofauna

This study shows temporal changes on wintering diet of the great cormorant (Phalacrocorax carbo) in Navarra over the last decade (1994 - 2004). Direct observation of birds feeding in different study areas were done over the study period. We show an increase of new aloctone ictiofauna in the wintering diet of this species over the last decade. The results suggest that diet composition of the great cormorant during the winter could be used as a good bioindicator of aquatic ecosystems.