Phenology and reproductive biology of the southern rockhopper penguin (Eudyptes chrysocome chrysocome) at Isla Pingüino (Santa Cruz province, Argentina)

Abstract

An essential trait to study population ecology of any species is reproduction, including parental care. In marine birds, these behaviors are well defined and stereotyped. Our study focused on analyzing those of the southern rockhopper penguins (Eudyptes chrysocome chrysocome), aiming to describe the breeding aspects of life history of the population of Isla Pingüino, Argentina. This species inhabits isolated, hardly accessible areas, which makes knowledge about them scarce. Here, we implemented a novel methodology, by marking individuals and using time-lapse cameras to get 24-hour records of complete breeding seasons. Their breeding cycle was in agreement with existing data; the adults followed a fixed pattern of nest and chick attendance. Females invested more time in incubating the eggs, while males were more dedicated to chick guarding. Feeding events were more frequently held by females, with males only contributing during the crèche period. The effect of weather conditions on chick survival was assessed, since uncommonly high air temperatures were reached during the study, causing unprecedented chick mass mortality. We found that there is a lethal temperature threshold for them, hence the occurrence of several extremely hot days increases the number of dead chicks. The methodology implemented has several benefits, being useful for future research, and can be applied in other colonies of the world to improve the quality of colony monitoring and detect potential threats of this vulnerable species.