Fledging rate in the Cormorant  Phalacrocorax carbo at the colony of Val Campotto (Po Delta, N-E Italy)

Grieco F.

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Cormorants Phalacrocorax carbo nesting at the Val Campotto colony occupied 270 nests in 1993. In 1992 and 1993, the number of f1edglings from 190 successful broods was recorded. Each brood was assigned to one of 3 laying periods defined within the breeding season (February-March, April-early May, late May-July), The mean number of f1edglings per nest was 2.81 ± 0.08 (SE) in 1992 and 2.80 ± 0.06 (SE) in 1993. In 1993 the fledgling production in late broods was lower than in early ones; no difference was found between nests at the centre and those at the edge of the colony, nor among cJusters of trees of different density. o cases of predation were observed. Data indicate a further growth of the colony. Some second brood attempts are also reported.