COMPOSICIÓN DE LA DIETA E IMPACTO DEL CORMORÁN GRANDE (PHALACROCORAX CARBO SINENSIS ) DURANTE LA INVERNADA EN LAS SALINAS DE SANTA POLA, ALICANTE, ESTE DE ESPAÑA

SUMMARY.—Population size and diet of the Great Cormorant (Phalacrocorax carbo sinensis) wintering in the Salinas Bras del Port (Santa Pola, Alicante, E Spain) . During the autumn of 1995 and the winter of 1996, population counts of Great Cormorants (P. carbo sinensis) wintering in the Salinas Bras del Port (Santa Pola, Alicante; Fig. 1) were carried out. Seasonal (Fig. 2) and daily (Fig. 3) changes in population size were characterised from these counts. The maximum number of birds was 579 in November. They concentrate in roosts located on small islands inside the saltpans. Wintering cormorants fed on the fish that are farmed in a semi-extensive regime in one part of the saltpans. The winter diet (estimated from pellet analyses) mainly consisted of mullets (80% of the biomass) and sparids (10% of the biomass; Fig. 4). The mean number of fish per pellet was 3.7 ± 5.6 (mean ± standard deviation), and the mean biomass 369.9 ± 290.6 g. We estimated that Cormorants consumed c.a. 18.3 tm of fish during the study period, that represented c.a. 66% of the production of the fish farm.