RESEARCH ARTICLE
Abstract Information about foraging speeds is particu-larly valuable when the impact of a predator species upon a community of prey has to be defined, as in the case of great cormorants. We measured the swim speed of 12 (six males and six females) free-ranging great cormorants Phalacrocorax carbo, f...
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ftciteseerx:oai:CiteSeerX.psu:10.1.1.661.1399 2023-05-15T16:28:13+02:00 RESEARCH ARTICLE The Pennsylvania State University CiteSeerX Archives application/pdf http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.661.1399 http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf en eng http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.661.1399 http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf Metadata may be used without restrictions as long as the oai identifier remains attached to it. http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf text ftciteseerx 2016-01-08T16:52:46Z Abstract Information about foraging speeds is particu-larly valuable when the impact of a predator species upon a community of prey has to be defined, as in the case of great cormorants. We measured the swim speed of 12 (six males and six females) free-ranging great cormorants Phalacrocorax carbo, foraging off the Greenland coast during the summer of 2003, using miniaturized data-loggers. Although mean body mass of males was 27 % greater than that of females, and mean swim speed of males were 29–57 % higher than that of females during foraging phases (but not descent phases) of dives, these differences in speeds were not significant due to high variances. Birds descended to the mean maximum depth of 4.7 m at an average speed of 1.6±0.5 m s1, a speed similar to that measured in captive cormorants in previous studies. Although bursts of up to 4 m s1 were recorded, speed usually decreased during the deepest (foraging) phase of dives, being on average 0.8±0.6 m s1. Speeds measured here should be taken with caution, because the large propeller loggers used to measure speed directly decreased descent speeds by up to 0.5 m s1 when compared to smaller depth-only loggers. Cormorants in Greenland seem to combine two searching strategies, one requiring low speed to scan the water column or benthos, and one requiring high speed to pursue prey. These two strategies depend on the two main habitats of their prey: pelagic or demersal. Text Greenland Unknown Greenland |
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Abstract Information about foraging speeds is particu-larly valuable when the impact of a predator species upon a community of prey has to be defined, as in the case of great cormorants. We measured the swim speed of 12 (six males and six females) free-ranging great cormorants Phalacrocorax carbo, foraging off the Greenland coast during the summer of 2003, using miniaturized data-loggers. Although mean body mass of males was 27 % greater than that of females, and mean swim speed of males were 29–57 % higher than that of females during foraging phases (but not descent phases) of dives, these differences in speeds were not significant due to high variances. Birds descended to the mean maximum depth of 4.7 m at an average speed of 1.6±0.5 m s1, a speed similar to that measured in captive cormorants in previous studies. Although bursts of up to 4 m s1 were recorded, speed usually decreased during the deepest (foraging) phase of dives, being on average 0.8±0.6 m s1. Speeds measured here should be taken with caution, because the large propeller loggers used to measure speed directly decreased descent speeds by up to 0.5 m s1 when compared to smaller depth-only loggers. Cormorants in Greenland seem to combine two searching strategies, one requiring low speed to scan the water column or benthos, and one requiring high speed to pursue prey. These two strategies depend on the two main habitats of their prey: pelagic or demersal. |
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The Pennsylvania State University CiteSeerX Archives |
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RESEARCH ARTICLE |
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RESEARCH ARTICLE |
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RESEARCH ARTICLE |
title_full |
RESEARCH ARTICLE |
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RESEARCH ARTICLE |
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research article |
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http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.661.1399 http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf |
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Greenland |
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Greenland |
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Greenland |
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Greenland |
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http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf |
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http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.661.1399 http://docyaounde.free.fr/stock/pdf/yan06marbiol1.pdf |
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Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
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1766017852614115328 |