Foraging effort and prey choice in cape gannets
In order to test the hypothesis that sardine Sardinops sagax are the preferred prey of Cape gannets Morus capensis, the link between foraging effort and prey choice was evaluated by simultaneously monitoring theactivity and the diet of adult birds attending chicks at Bird Island, Algoa Bay, South Af...
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African Journal of Marine Science
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ftjafricanj:oai:ojs.ajol.info:article/66494 2023-05-15T15:44:42+02:00 Foraging effort and prey choice in cape gannets NJ Adams NTW Klages 2011-05-24 application/pdf http://ajol.info/index.php/ajms/article/view/66494 en eng African Journal of Marine Science http://ajol.info/index.php/ajms/article/view/66494 Copyright for articles published in this journal is retained by the publisher. African Journal of Marine Science; Vol 21 (1999) Peer-reviewed Article 2011 ftjafricanj 2011-05-28T23:34:36Z In order to test the hypothesis that sardine Sardinops sagax are the preferred prey of Cape gannets Morus capensis, the link between foraging effort and prey choice was evaluated by simultaneously monitoring theactivity and the diet of adult birds attending chicks at Bird Island, Algoa Bay, South Africa. Foraging trip durations were bimodally distributed. Most foraging trips of Cape gannets were completed within 24 h. Metered gannets spent c. 40% of this time flying. In all, nine prey species were recovered from the stomachs of metered birds. The diet was dominated by the commercially important sardine Sardinops sagax and anchovy Engraulis capensis. Food mass intake by foraging Cape gannets was not correlated with foraging trip duration or time flying, consistent with a patchy distribution of food. Cape gannets returning with sardine tended to have shorter foraging trips and spent significantly less time flying than birds returning with other prey, thereby maximizing net energy intake. Sardine seem to be the preferred (most profitable) prey and, consequently, their relative proportion in gannetstomachs may reflect their absolute availability at spatial scales equivalent to the bird’s foraging range. Article in Journal/Newspaper Bird Island AJOL - African Journals Online Bird Island ENVELOPE(-38.060,-38.060,-54.004,-54.004) |
institution |
Open Polar |
collection |
AJOL - African Journals Online |
op_collection_id |
ftjafricanj |
language |
English |
description |
In order to test the hypothesis that sardine Sardinops sagax are the preferred prey of Cape gannets Morus capensis, the link between foraging effort and prey choice was evaluated by simultaneously monitoring theactivity and the diet of adult birds attending chicks at Bird Island, Algoa Bay, South Africa. Foraging trip durations were bimodally distributed. Most foraging trips of Cape gannets were completed within 24 h. Metered gannets spent c. 40% of this time flying. In all, nine prey species were recovered from the stomachs of metered birds. The diet was dominated by the commercially important sardine Sardinops sagax and anchovy Engraulis capensis. Food mass intake by foraging Cape gannets was not correlated with foraging trip duration or time flying, consistent with a patchy distribution of food. Cape gannets returning with sardine tended to have shorter foraging trips and spent significantly less time flying than birds returning with other prey, thereby maximizing net energy intake. Sardine seem to be the preferred (most profitable) prey and, consequently, their relative proportion in gannetstomachs may reflect their absolute availability at spatial scales equivalent to the bird’s foraging range. |
format |
Article in Journal/Newspaper |
author |
NJ Adams NTW Klages |
spellingShingle |
NJ Adams NTW Klages Foraging effort and prey choice in cape gannets |
author_facet |
NJ Adams NTW Klages |
author_sort |
NJ Adams |
title |
Foraging effort and prey choice in cape gannets |
title_short |
Foraging effort and prey choice in cape gannets |
title_full |
Foraging effort and prey choice in cape gannets |
title_fullStr |
Foraging effort and prey choice in cape gannets |
title_full_unstemmed |
Foraging effort and prey choice in cape gannets |
title_sort |
foraging effort and prey choice in cape gannets |
publisher |
African Journal of Marine Science |
publishDate |
2011 |
url |
http://ajol.info/index.php/ajms/article/view/66494 |
long_lat |
ENVELOPE(-38.060,-38.060,-54.004,-54.004) |
geographic |
Bird Island |
geographic_facet |
Bird Island |
genre |
Bird Island |
genre_facet |
Bird Island |
op_source |
African Journal of Marine Science; Vol 21 (1999) |
op_relation |
http://ajol.info/index.php/ajms/article/view/66494 |
op_rights |
Copyright for articles published in this journal is retained by the publisher. |
_version_ |
1766379076275142656 |