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Intra- and inter-individual changes in little penguin diving and isotopic composition over the breeding season
journal contributionposted on 2023-05-21, 08:31 authored by Amelineau, F, Saraux, C, Ropert-Coudert, Y, Kato, A, Hobson, KA, Ben Raymond, Zimmer, I, Chiaradia, A
Seabirds allocate different amounts of energy to reproduction throughout the breeding season, depending on the trade-off between their own needs and those of their chicks and/or changes in environmental conditions. Provisioning parents therefore modulate their foraging behaviour and diet accordingly. However, for diving seabirds, many studies have extrapolated from individuals monitored over a short period and then assumed the observed patterns were representative of the birds' foraging activity over the entire breeding stage/season. To address this shortcoming, we monitored continuously the diving performance of ten male little penguins from incubation to chick fledging. Simultaneously, isotopic composition was examined using d15N and d13C values from whole blood samples collected every 3 weeks. Birds dived more frequently but performed shallower and shorter dives as the season progressed. The guard period was especially different, with birds spending a consistently smaller proportion of time at the bottom and performing fewer prey pursuits, compared to other periods. Isotopic composition varied less within the season, although there was a slight tendency for d15N values to decrease through time. Finally, isotopic values were highly repeatable within individuals, suggesting that individuals specialized on different prey and in different areas. Diving was less repeatable within individuals but still explained a small but significant part of the variance in blood isotopic values. Our results suggest that it is important to take into account individual variability over the course of the breeding season, as well as timing of bio-logger deployment within a stage when designing bio-logging studies.
Publication titleMarine Biology
Department/SchoolInstitute for Marine and Antarctic Studies
Place of publication175 Fifth Ave, New York, USA, Ny, 10010
Rights statement© The Author(s), under exclusive licence to Springer-Verlag GmbH Germany