Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis
Consistent diel patterns in foraging depths have been recorded in several avian predators which feed on pelagic prey, but nothing is known about such effects in bottom feeding seabirds. In the underwater environment, illumination is influenced primarily by water depth. Thus a predator's ability...
Published in: | Marine Ecology Progress Series |
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1999
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Online Access: | http://nora.nerc.ac.uk/id/eprint/503831/ https://doi.org/10.3354/meps188219 |
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ftnerc:oai:nora.nerc.ac.uk:503831 2023-05-15T15:45:00+02:00 Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis Wanless, Sarah Finney, Suzanne K. Harris, Michael P. McCafferty, Dominic J. 1999 http://nora.nerc.ac.uk/id/eprint/503831/ https://doi.org/10.3354/meps188219 unknown Inter-Research Wanless, Sarah; Finney, Suzanne K.; Harris, Michael P.; McCafferty, Dominic J. 1999 Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis. Marine Ecology Progress Series, 188. 219-224. https://doi.org/10.3354/meps188219 <https://doi.org/10.3354/meps188219> Publication - Article PeerReviewed 1999 ftnerc https://doi.org/10.3354/meps188219 2023-02-04T19:38:02Z Consistent diel patterns in foraging depths have been recorded in several avian predators which feed on pelagic prey, but nothing is known about such effects in bottom feeding seabirds. In the underwater environment, illumination is influenced primarily by water depth. Thus a predator's ability to exploit feeding areas located in deep water could, theoretically, be constrained by light availability. We investigated the effects of the diel light cycle on the diving behaviour of 2 species of bottom feeding seabird: the blue-eyed shag Phalacrocorax atriceps and the European shag P. aristotelis. Time-based data loggers were attached to 22 blue-eyed shags and 21 European shags and used to obtain detailed and concurrent records of foraging conditions in terms of depth and illumination during the chick-rearing period. Both species were exclusively diurnal feeders. There were marked differences in mean foraging depth and foraging illumination between individual birds (blue-eyed shag: ranges 3.2 to 73.3 m and -0.3 to 2.0 log10 lx; European shag: 8.5 to 34.6 m and 0.9 to 2.0 log10 lx). Superimposed on this variation was a consistent effect whereby individuals significantly modified their diving behaviour in response to the diel light cycle, in accord with the prediction that foraging depths would be maximised when ambient illumination was highest. However, it appeared that individuals did not fully exploit the potential of this diel effect since, although foraging depths in the middle of the day were generally deeper, the associated illumination was higher than that experienced during shallower dives made earlier or later in the day. Nevertheless, we believe that diel effects can play an important role in shaping the foraging behaviour of bottom feeding, avian predators. Article in Journal/Newspaper Blue Eyed Shag Phalacrocorax atriceps Natural Environment Research Council: NERC Open Research Archive Marine Ecology Progress Series 188 219 224 |
institution |
Open Polar |
collection |
Natural Environment Research Council: NERC Open Research Archive |
op_collection_id |
ftnerc |
language |
unknown |
description |
Consistent diel patterns in foraging depths have been recorded in several avian predators which feed on pelagic prey, but nothing is known about such effects in bottom feeding seabirds. In the underwater environment, illumination is influenced primarily by water depth. Thus a predator's ability to exploit feeding areas located in deep water could, theoretically, be constrained by light availability. We investigated the effects of the diel light cycle on the diving behaviour of 2 species of bottom feeding seabird: the blue-eyed shag Phalacrocorax atriceps and the European shag P. aristotelis. Time-based data loggers were attached to 22 blue-eyed shags and 21 European shags and used to obtain detailed and concurrent records of foraging conditions in terms of depth and illumination during the chick-rearing period. Both species were exclusively diurnal feeders. There were marked differences in mean foraging depth and foraging illumination between individual birds (blue-eyed shag: ranges 3.2 to 73.3 m and -0.3 to 2.0 log10 lx; European shag: 8.5 to 34.6 m and 0.9 to 2.0 log10 lx). Superimposed on this variation was a consistent effect whereby individuals significantly modified their diving behaviour in response to the diel light cycle, in accord with the prediction that foraging depths would be maximised when ambient illumination was highest. However, it appeared that individuals did not fully exploit the potential of this diel effect since, although foraging depths in the middle of the day were generally deeper, the associated illumination was higher than that experienced during shallower dives made earlier or later in the day. Nevertheless, we believe that diel effects can play an important role in shaping the foraging behaviour of bottom feeding, avian predators. |
format |
Article in Journal/Newspaper |
author |
Wanless, Sarah Finney, Suzanne K. Harris, Michael P. McCafferty, Dominic J. |
spellingShingle |
Wanless, Sarah Finney, Suzanne K. Harris, Michael P. McCafferty, Dominic J. Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
author_facet |
Wanless, Sarah Finney, Suzanne K. Harris, Michael P. McCafferty, Dominic J. |
author_sort |
Wanless, Sarah |
title |
Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
title_short |
Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
title_full |
Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
title_fullStr |
Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
title_full_unstemmed |
Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis |
title_sort |
effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag phalacrocorax atricepsand the european shag p. aristotelis |
publisher |
Inter-Research |
publishDate |
1999 |
url |
http://nora.nerc.ac.uk/id/eprint/503831/ https://doi.org/10.3354/meps188219 |
genre |
Blue Eyed Shag Phalacrocorax atriceps |
genre_facet |
Blue Eyed Shag Phalacrocorax atriceps |
op_relation |
Wanless, Sarah; Finney, Suzanne K.; Harris, Michael P.; McCafferty, Dominic J. 1999 Effect of the diel light cycle on the diving behaviour of two bottom feeding marine birds:the blue-eyed shag Phalacrocorax atricepsand the European shag P. aristotelis. Marine Ecology Progress Series, 188. 219-224. https://doi.org/10.3354/meps188219 <https://doi.org/10.3354/meps188219> |
op_doi |
https://doi.org/10.3354/meps188219 |
container_title |
Marine Ecology Progress Series |
container_volume |
188 |
container_start_page |
219 |
op_container_end_page |
224 |
_version_ |
1766379372427608064 |