Asincronía de puesta y reposición de la nidada en el Cormorán Cuello Negro (Phalacrocorax magellanicus): ？evidencias de las características de su fuente de alimento?

we studied the breeding biology of the rock shag (phalacrocorax magellanicus) at punta loma colony, chubut, argentina, during 2001 and 2002 breeding seasons. the egg laying period was long (3-4 months) and asynchronous, while fledging success was low (50%). during the first breeding season, the number of fledglings per nest was not related to laying date, while during the second breeding season there was a reduction in the fledging success of the pairs that laid their eggs late in the season. a high percentage of couples renested after loosing the first clutch (16-22%). in both seasons, the number of chicks fledged in replacement clutches was similar to that in first clutches. the extended and asynchronous egg-laying period, combined with a high rate of renesting (with a fledging success similar to that of single-laying couples), and the low relationship observed between breeding success and laying date, supports the idea of a highly stable and predictable food source for the rock shag.