Diet segregation in Adélie penguins: some individuals attempt to overcome colony-induced and annual foraging challenges

• Main Authors: 3rd World Seabird Conference 2021, Massaro, Melanie
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Underline Science Inc. 2021
• Subjects: Ecology; FOS Biological sciences; Animal Science; Ross Island; Crozier; Ballard; Cape Bird; Cape Crozier; Amélie; Antarc*; Antarctica
• Online Access: https://dx.doi.org/10.48448/xvrk-3v60; https://underline.io/lecture/34615-diet-segregation-in-adelie-penguins-some-individuals-attempt-to-overcome-colony-induced-and-annual-foraging-challenges

Abstract: Intraspecific competition for food can be especially high in colonial breeding seabirds. To minimize colony-induced or annual foraging challenges, the diet may vary among individuals, but few studies have simultaneously investigated the effects of both extrinsic conditions (e.g. colony, year effects) and parameters of an individual (e.g. sex, age, individual quality) on diet in seabirds. Using stable isotope analyses, we studied the diet of 214 Adélie penguins of known sex, age and breeding quality, nesting in two colonies on Ross Island, Antarctica, over three breeding seasons. During the study, δ15N and δ13C isotope values were lower in penguins breeding at Cape Crozier compared to those at Cape Bird, resulting in a difference in estimated prey proportions. Cape Bird penguins consistently consumed more energy-rich silverfish, while birds at Cape Crozier ate more crystal krill. We also found inter-annual differences in diet, with a higher dietary fish proportion in both colonies during 2011. Males had significantly higher δ15N values, indicating that males consumed more fish than females. This sexual segregation in diet was particularly pronounced at Cape Bird, where the overall isotopic niche was wider than at Cape Crozier. Differences in diet among adults of varying ages only existed at Cape Bird, where middle-aged penguins consumed more fish than old and young penguins. This study provides evidence that penguin diet is largely driven by annual, seasonal and local abundances of prey, with only some individuals selectively foraging for more nutritional prey if prey choices are present. Authors: Melanie Massaro¹, David Ainley², Jarrod Santora³, Petra Quillfeldt⁴, Amélie Lescroël⁵, Amy Whitehead⁶, Arvind Varsani⁷, Grant Ballard⁵, Phil Lyver⁸ ¹Charles Sturt University, ²H.T. Harvey & Associates, ³University of California, ⁴Justus Liebig University Giessen, ⁵Point Blue Conservation Science, ⁶National Institute of Water and Atmospheric Research, ⁷Arizona State University, ⁸Manaaki Whenua Landcare Research