Foraging Before Spring Migration and Before Breeding in Common Eiders: Does Hyperphagia Occur?
Abstract Foraging performance of Common Eider (Somateria mollissima) was studied to find out if hyperphagia occurs before migration and breeding in this species. Diving efficiency and time spent feeding were quantified concomitantly for two subspecies that differ in the timing of their reproduction...
| Published in: | The Condor |
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| Main Author: | |
| Format: | Article in Journal/Newspaper |
| Language: | English |
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Oxford University Press (OUP)
2001
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| Online Access: | http://dx.doi.org/10.1093/condor/103.3.633 http://academic.oup.com/condor/article-pdf/103/3/633/29710627/condor0633.pdf |
| Summary: | Abstract Foraging performance of Common Eider (Somateria mollissima) was studied to find out if hyperphagia occurs before migration and breeding in this species. Diving efficiency and time spent feeding were quantified concomitantly for two subspecies that differ in the timing of their reproduction and migration. The foraging performance of female S. m. dresseri preparing for breeding and female S. m. borealis preparing for migration were compared with their male counterparts, which are known to achieve energy balance during these periods. Female dresseri spent 41% of their time feeding and made 404 dives daily, for a total of 169 min spent underwater each day. Female dresseri spent more time diving than did males by about one hour each day. There were no detectable differences in the foraging performances of male and female borealis, probably because the body mass of migrating females increased only slightly prior to migration. Hyperphagia in breeding female dresseri appears to be the main cause of increased body mass, although other mechanisms may play a role. Quête Alimentaire Chez l'Eider à Duvet Avant la Migration Printanière et la Nidification: Est-Il Possible de Déceler un Phénomène d'Hyperphagie? Résumé. Le quête alimentaire de l'Eider à duvet (Somateria mollissima) fut étudiée au printemps avant la migration et avant la nidification dans le but de déceler, s'il y a lieu, un phénomène d'hyperphagie chez cette espèce. Le temps passé à s'alimenter et l'efficacité de la plongée furent quantifiés simultanément pour deux sous-espèces qui diffèrent quant à leur chronologie de nidification et de migration. La quête alimentaire des femelles S. m. dresseri, se préparant pour la nidification, et des femelles S. m. borealis, se préparant pour la migration, fut comparée avec celle des mâles de chacune des sous-espèces respectives. Les mâles furent utilisés comme “témoins” puisqu'il y a des évidences que ces derniers maintiennent l'équilibre énergétique durant cette période. Les femelles dresseri ont passé en moyenne ... |
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