THE BREEDING BIOLOGY OF PYGMY CORMORANTS (PHALACROCORAX-PYGMEUS), A VULNERABLE BIRD SPECIES, AT LAKE KERKINI, NORTHERN GREECE

The Pygmy Cormorant (Phalacrocorax pygmeus) is a litile-known vulnerab le species with a restricted Palearctic distribution. From 1988 to 199 0, its bleeding biology was examined at the artificial Lake of Kerkini , northern Greece where it nests in a mixed-species colony composed of 12 species of waterbird. The height of the cormorant nests above the ground varied from 2.2 to 5.5 m. The water depth varied from 1.0 m at the beginning of the laying period to 3.0 m by the middle of the breed ing season. Mean egg measurements were 46.5 x 30.6 nm. Mean clutch sir e was 5.3 eggs (range: 2 to 8); clutches of 5 and 6 were the most comm on. Almost 77% of the 867 eggs laid in 165 nests observed over three y ears hatched. Survival of chicks, to three weeks of age was 69% of the eggs laid and 89.8% of eggs hatched. Flooding of nests was the major mortality factor. Decreasing the maximum water level and the duration of the flooding at that level is necessary to prevent the destruction of the flooded forest.