Aspects of the breeding biology of the Red-legged Cormorant Phalacrocorax gaimardi on the Atlantic coast of South America

FRERE, E. & GANDINI, P.

Marine Ornithology

South African Seabird Group

Lugar: Cape Town; Año: 2001 vol. 29 p. 67 - 70

1018-3337

Red-legged Cormorants breed in Argentina, Chile and Peru. In Argentina their breeding range is restricted to a short section of coastline in southern Patagonia. We studied two colonies located on high rocky cliffs, 2 to 4 m above the high tide line. At one colony, nests were prtected from prevailing winds whereas at the other colony most of the nests were exposed. Of active nests, 15% had two eggs, 66% had three eggs, and 19% had four eggs, to give a mean clutch of 3.04+-0.47. Egg dimensions were 60+-2.4 X 37.1+-1.4 mm. The incubation period ranged from 34 to 38 days with chicks hatching from mid-November to the first week of December. Red-legged Cormorants lay more and smaller eggs than do those of two sympatric cormorant species, the Rock Cormorant and the Imperial Cormorant, probably as a result of diferences in foraging ranges. Avian predation on eggs seems to be an important mortality factor for this species and wind has also an important effect on breeding success, possibly exacerbating avian predation.