Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep
Sex differences in foraging behaviour have been explained by size dimorphism and/or avoidance of inter-sexual competition for depletable resources. To distinguish between these 2 hypotheses, we examined how intrinsic factors (sex-related differences) and extrinsic factors (year differences) shape th...
Published in: | Marine Ecology Progress Series |
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Language: | English |
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Online Access: | https://jlupub.ub.uni-giessen.de//handle/jlupub/209 https://doi.org/10.3354/meps09058 https://doi.org/10.22029/jlupub-155 |
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ftunivgiessen:oai:jlupub.ub.uni-giessen.de:jlupub/209 2023-07-30T04:06:20+02:00 Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep Quillfeldt, Petra Schroff, Simone Noordwijk, Hendrika J. van Michalik, Andreas Ludynia, Katrin Masello, Juan F. 2011 application/pdf https://jlupub.ub.uni-giessen.de//handle/jlupub/209 https://doi.org/10.3354/meps09058 https://doi.org/10.22029/jlupub-155 en eng https://doi.org/10.3354/meps09058 https://jlupub.ub.uni-giessen.de//handle/jlupub/209 http://dx.doi.org/10.22029/jlupub-155 Diving behaviour Behavioural plasticity Optimal foraging Stable isotope analysis Stable isotope mixing model Sexual size dimorphism Phalacrocorax atriceps ddc:570 article 2011 ftunivgiessen https://doi.org/10.3354/meps0905810.22029/jlupub-155 2023-07-16T22:26:56Z Sex differences in foraging behaviour have been explained by size dimorphism and/or avoidance of inter-sexual competition for depletable resources. To distinguish between these 2 hypotheses, we examined how intrinsic factors (sex-related differences) and extrinsic factors (year differences) shape the foraging behaviour of size-dimorphic imperial shags Phalacrocorax atriceps albiventer breeding at New Island, Falkland Islands/Islas Malvinas. We deployed time-depth and compass loggers to male and female imperial shags over 3 consecutive chick-feeding seasons. Males and females partly overlapped in coastal foraging areas, which were used mainly for benthic diving. Males additionally used offshore areas over deep water for shallow pelagic diving, suggesting that spatial segregation is involved in the avoidance of inter-sexual competition for food. Stable isotope data suggested differences in prey composition between the sexes, with consistently higher trophic levels in males, as expected for their larger size. Males were 27% heavier than females and reached greater maximum dive depths (98.9 ± 5.3 m) than females (54.1 ± 2.9 m). However, contrary to predictions based on body size dimorphism, the median dive depths of males were similar to those of females. While females used mainly benthic diving, males were more flexible in their benthic and pelagic foraging behaviour. Females also carried out more dives per day in all years, and deeper and longer dives than males in one year. As dive parameters differed strongly among the years, our results suggest that body size dimorphism and the avoidance of inter-sexual competition for food are involved in the evolution of sex-related differences in foraging in this species. Article in Journal/Newspaper Phalacrocorax atriceps Justus-Liebig-Universität Giessen: JLUpub Marine Ecology Progress Series 428 271 287 |
institution |
Open Polar |
collection |
Justus-Liebig-Universität Giessen: JLUpub |
op_collection_id |
ftunivgiessen |
language |
English |
topic |
Diving behaviour Behavioural plasticity Optimal foraging Stable isotope analysis Stable isotope mixing model Sexual size dimorphism Phalacrocorax atriceps ddc:570 |
spellingShingle |
Diving behaviour Behavioural plasticity Optimal foraging Stable isotope analysis Stable isotope mixing model Sexual size dimorphism Phalacrocorax atriceps ddc:570 Quillfeldt, Petra Schroff, Simone Noordwijk, Hendrika J. van Michalik, Andreas Ludynia, Katrin Masello, Juan F. Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
topic_facet |
Diving behaviour Behavioural plasticity Optimal foraging Stable isotope analysis Stable isotope mixing model Sexual size dimorphism Phalacrocorax atriceps ddc:570 |
description |
Sex differences in foraging behaviour have been explained by size dimorphism and/or avoidance of inter-sexual competition for depletable resources. To distinguish between these 2 hypotheses, we examined how intrinsic factors (sex-related differences) and extrinsic factors (year differences) shape the foraging behaviour of size-dimorphic imperial shags Phalacrocorax atriceps albiventer breeding at New Island, Falkland Islands/Islas Malvinas. We deployed time-depth and compass loggers to male and female imperial shags over 3 consecutive chick-feeding seasons. Males and females partly overlapped in coastal foraging areas, which were used mainly for benthic diving. Males additionally used offshore areas over deep water for shallow pelagic diving, suggesting that spatial segregation is involved in the avoidance of inter-sexual competition for food. Stable isotope data suggested differences in prey composition between the sexes, with consistently higher trophic levels in males, as expected for their larger size. Males were 27% heavier than females and reached greater maximum dive depths (98.9 ± 5.3 m) than females (54.1 ± 2.9 m). However, contrary to predictions based on body size dimorphism, the median dive depths of males were similar to those of females. While females used mainly benthic diving, males were more flexible in their benthic and pelagic foraging behaviour. Females also carried out more dives per day in all years, and deeper and longer dives than males in one year. As dive parameters differed strongly among the years, our results suggest that body size dimorphism and the avoidance of inter-sexual competition for food are involved in the evolution of sex-related differences in foraging in this species. |
format |
Article in Journal/Newspaper |
author |
Quillfeldt, Petra Schroff, Simone Noordwijk, Hendrika J. van Michalik, Andreas Ludynia, Katrin Masello, Juan F. |
author_facet |
Quillfeldt, Petra Schroff, Simone Noordwijk, Hendrika J. van Michalik, Andreas Ludynia, Katrin Masello, Juan F. |
author_sort |
Quillfeldt, Petra |
title |
Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
title_short |
Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
title_full |
Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
title_fullStr |
Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
title_full_unstemmed |
Flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
title_sort |
flexible foraging behaviour of a sexually dimorphic seabird: large males do not always dive deep |
publishDate |
2011 |
url |
https://jlupub.ub.uni-giessen.de//handle/jlupub/209 https://doi.org/10.3354/meps09058 https://doi.org/10.22029/jlupub-155 |
genre |
Phalacrocorax atriceps |
genre_facet |
Phalacrocorax atriceps |
op_relation |
https://doi.org/10.3354/meps09058 https://jlupub.ub.uni-giessen.de//handle/jlupub/209 http://dx.doi.org/10.22029/jlupub-155 |
op_doi |
https://doi.org/10.3354/meps0905810.22029/jlupub-155 |
container_title |
Marine Ecology Progress Series |
container_volume |
428 |
container_start_page |
271 |
op_container_end_page |
287 |
_version_ |
1772818886261997568 |