Effects of Nest Density on Breeding Success in a Colony of Magellanic Penguins (Spheniscus magellanicus)

Publisher Website
Google Scholar
Abstract
Population parameters for Magellanic penguins were recorded during six reproductive seasons (1976-82) at the Punta Tombo colony at Chubut, Argentina. Laying, hatching, fledging and corresponding mortality rates were calculated for areas of different nest density. Breeding seemed more successful at densities of 16-40 nests per 100 m2 than in lower or higher nest-density areas. Clutch size averaged 1.87 (.+-.0.09 SD) eggs. Hatching success was 53.5% and fledging success was 44% giving an overall reproduction success of 23.5%. The principal causes of loss of eggs and chicks were parental desertions resulting in predation by gulls, or starvation of chicks. Egg mortality increased after the 33rd incubation day and chicks were at greatest risk of predation by gulls, or starvation ov chicks. Egg mortality increased after the 33rd incubation day and chicks were at greatest risk of predation during the first week after hatching. The likelihood of death showed two speaks, at the creches stage (20-23 d) and during the down moult (52-54 d). At both times, delays or absences of attendant parents after feeding trips were the principal causes of mortality.

This publication has 0 references indexed in Scilit: