Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2021
Erindi/veggspjald / Talk/poster E86
Höfundar / Authors: Eilidh S. O'Brien (1), Patrick J.O. Miller (2), Filipa I.P. Samarra (3)
Starfsvettvangur / Affiliations: 1. School of Biology, University of St. Andrews, St. Andrews, KY16 9ST, UK; 2. Sea Mammal Research Unit, Scottish Oceans Institute, University of St. Andrews, St. Andrews, KY16 8LB, UK; 3. University of Iceland’s Institute of Research Centres, Ægisgata 2, 900 Vestmannaeyjar, Iceland
Kynnir / Presenter: Eilidh O'Brien
Understanding the social structure of long-lived, social animals requires long time-series. Recently, a study of Icelandic killer whales found that their society is divided into clusters rather than a hierarchical structure as in other, better-studied populations. However, that study was based on a relatively small dataset (2008-2015) which included data from both summer and winter. To investigate seasonal associations over a longer timescale, we used photographs taken in summer herring spawning grounds between 2008-2018 and analysed associations between individual killer whales using the half-weight index (HWI). The results supported previous findings that this population’s social structure separates into many interconnected clusters rather than stratified tiers. However, the social network of these killer whales was more strongly interconnected than previously reported: although the majority of associations between individuals remained weak (35.33% of all associations HWI ≤ 0.1; 3.56% HWI ≥ 0.5) we found stronger associations within the population than (mean HWI ± SD = 0.18 ± 0.06; previous mean HWI ± SD = 0.02 ± 0.01). This suggests there may be seasonal variation within social associations. Analysis of association patterns throughout time reinforced previous findings of a mixture of permanent and temporary associations. These results indicate that killer whale social structure in Iceland is to some extent flexible, and that social groups are liable to change over time.