Aspectos de la biología reproductiva del Ostrero Negro Haematopus ater en las islas Isabel, Bahía Bustamante, Chubut

In our study about the breeding biology of the Blackish Oystercatcher Haematopus ater, conducted during 1991/92 breeding season, the laying period started at the end of the second week of October and finished at the end of November. Mean clutch size was 1.8 (sd= 0.4, n= 26, modal clutch size= 2), while the mean laying interval between the first and second eggs laid in the same clutch was 2.8 days (s.d.= 1.4, n= 16). The laying-hatching intervals averaged : 28 days (s.d.= 2.5, n= 11). Hatchings occured between the second week of November and the first week of December and mean hatching interval was 1.8 days (s.d.= 0.5, n= 5).