Ecological Segregation of Adelie, Gentoo, and Chinstrap Penguins at King George Island, Antarctica

• Published in: Ecology
• Main Authors: Trivelpiece, Wayne Z., Trivelpiece, Susan G., Volkman, Nicholas J.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1987
• Subjects: Antarctic; King George Island; Antarc*; Antarctica
• Online Access: http://dx.doi.org/10.2307/1939266; http://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1939266; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.2307%2F1939266; https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.2307/1939266

Ecological segregation among Adelie, Gentoo, and Chinstrap penguins during summer results from differences in breeding chronology, foraging behaviors, and life history tactics. To determine the importance of these factors in segregating the niches of the three species, we collected data on their population size, breeding success, breeding chronology, feeding frequency, and foraging range. Gentoo Penguins feed inshore and are deep divers. Their small populations probably reflect the comparatively large amount of food they need to rear chicks and the small foraging range that is dictated by short nest relief schedules and nonfasting behaviors. Their deep diving ability enables them to exploit a niche that is unavailable to their more abundant congeners. Adelie and Chinstrap penguins are shallow—diving, offshore foragers that avoid competition by differences in breeding chronology, prebreeder behaviors, and molting strategies. Adelie chicks fledge just as Chinstrap chicks reach creche age. Different migration times and molting locations further reduce niche overlap. The ultimate factors responsible for this tropic segregation may be unrelated to these proximate factors, however. Nonmigratory behavior, short nest reliefs, nonfasting, and slow growth of chicks may be adaptations to the mild conditions experienced by Gentoo Penguins in their sub—Antarctic range. The differences in Adelie and Chinstrap breeding time may reflect adaptation of Adelies to early breeding in the harsh, short summer of the continental Antarctic, and adaptation of Chinstraps to later breeding in the milder Maritime Antarctic. We found no evidence to suggest that the niches of the Pygoscelis penguins were influenced by competition for food, and suggest that adaptation to conditions in the center of their respective distributions is the primary cause affecting ecological segregation in areas of sympatry.