Authors: Kyle Hamish Elliott Roger D Bull Anthony J Gaston Gail K Davoren
Publish Date: 2009/07/08
Volume: 63, Issue: 12, Pages: 1773-1785
Abstract
How predators vary search patterns in response to prey predictability is poorly known For example marine invertebrates may be predictable but of low energy value while fish may be of higher energy value but unpredictable at large pelagic schools or small solitary benthics spatial scales We investigated the search patterns of the thickbilled murre Uria lomvia an Arctic seabird feeding on invertebrates pelagic fish or benthic fish Foraging ranges at the Coats Island colony are generally smaller 240 min per trip than at larger colonies and many birds specialize in foraging tactics and diet Underwater search times for benthic fish were higher than for pelagic fish or invertebrates while abovewater search times for pelagic fish were higher than for benthic fish or invertebrates There were few stops during trips Total trip time flying time number of flights and number of dives were intercorrelated and increased with prey energy content suggesting that longer trips involved fewer prey encounters due to selection of higherquality but rarer prey items Flight times were not Lévydistributed and seabirds may have used arearestricted searches The high degree of specialization apparent absence of information center effects and reduced abovewater searching times may be linked to the relatively small colony size and the resulting short commuting distances to feeding areas leading to greater prey predictability We concluded that prey predictability over various scales affected predator search patternsWe thank B Addison K Ashbrook M Barrueto A Hargreaves M Hipfner S Jacobs G Lancton A Moody J Provencher A Ronson K Skebo P Smith K Woo and P Woodward for help in the field A Fromevitch K Hedges and P Turko helped with data compilation J Nakoolak kept us safe from bears A Burger D Gillis and an anonymous reviewer provided excellent comments on an earlier version of the manuscript KHE benefited from funding provided by NSERC Postgraduate M Award NSERC Northern Research Internship Andrew Taylor Northern Research Grant Mountain Equipment Coop Studentship Arctic Institute of North America Grantinaid Malcolm Ramsay Award Frank M Chapman Memorial Fund Society of Canadian Ornithologists/Bird Studies Canada Taverner Award and the Northern Scientific Training Program through the Department of Indian Affairs and Northern Development The Canadian Wildlife Service Migratory Birds Division 2007–2008 International Polar Year the Polar Continental Shelf Project and the University of Manitoba also funded this project R Armstrong at the Nunavut Research Institute M Mallory at the Canadian Wildlife Service Northern Research Division and C Eberl at the Canadian Wildlife Service in Ottawa provided logistical support All procedures were approved under the guidelines of the Canadian Committee for Animal Care Protocol Number F04030
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