Foraging behaviour of the Imperial Cormorant Phalacrocorax atriceps in Patagonia, Argentina
The present study revealed information on the foraging activity of breeding Imperial Cormorants. The analysis of the data allowed a precise quantification of the time budget underwater and showed that Imperial Cormorants partition their time underwater in a descent, bottom and ascent phase. Their pe...
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| Format: | Thesis |
| Language: | English |
| Published: |
2004
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| Online Access: | https://oceanrep.geomar.de/id/eprint/3481/ https://oceanrep.geomar.de/id/eprint/3481/1/Dipl.%202004%20Dix,A.pdf |
| Summary: | The present study revealed information on the foraging activity of breeding Imperial Cormorants. The analysis of the data allowed a precise quantification of the time budget underwater and showed that Imperial Cormorants partition their time underwater in a descent, bottom and ascent phase. Their percentage allocation of time to the different phases of the dive cycle varied substantially as a function of maximum dive depth so that foraging efficiency was highest at shallower depths and lowest at deeper depths. Imperial Cormorants foraged over the broad depth range of 5-70 m, despite a lower foraging efficiency when exploiting deeper waters. This observation intimates that there must be an advantage for them to do so. The results suggest that the foraging behaviour and ultimately the optimal foraging strategy employed by Imperial Cormorants is influenced by several environmental factors such as water depth, prey density and intraor inter-specific competition. Further investigations linking cormorants' feeding activity, prey distribution and environmental factors will undoubtedly help to clarify the foraging strategies employed by Imperial Cormorants. |
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