Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators

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dc.contributor.authorThaxter, Chris Ben_ZA
dc.contributor.authorDaunt, Francisen_ZA
dc.contributor.authorGrémillet, Daviden_ZA
dc.contributor.authorHarris, Mike Pen_ZA
dc.contributor.authorBenvenuti, Silvanoen_ZA
dc.contributor.authorWatanuki, Yutakaen_ZA
dc.contributor.authorHamer, Keith Cen_ZA
dc.contributor.authorWanless, Sarahen_ZA
dc.date.accessioned2015-11-16T04:10:55Z
dc.date.available2015-11-16T04:10:55Z
dc.date.issued2013en_ZA
dc.description.abstractUnderstanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot ( Uria aalge ) and razorbill ( Alca torda ) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5±0.8 items per dive (0.8±0.4 and 1.1±0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7±2.4 items per dive (4.9±3.1 and 7.3±4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in predicting likely impacts of environmental change on marine higher predators dependent on species-specific foraging ecologies.en_ZA
dc.identifier.apacitationThaxter, C. B., Daunt, F., Grémillet, D., Harris, M. P., Benvenuti, S., Watanuki, Y., ... Wanless, S. (2013). Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators. <i>PLoS One</i>, http://hdl.handle.net/11427/15015en_ZA
dc.identifier.chicagocitationThaxter, Chris B, Francis Daunt, David Grémillet, Mike P Harris, Silvano Benvenuti, Yutaka Watanuki, Keith C Hamer, and Sarah Wanless "Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators." <i>PLoS One</i> (2013) http://hdl.handle.net/11427/15015en_ZA
dc.identifier.citationThaxter, C. B., Daunt, F., Grémillet, D., Harris, M. P., Benvenuti, S., Watanuki, Y., ... & Wanless, S. (2012). Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators. PloS one, 8(11), e79915-e79915. doi:10.1371/journal.pone.0079915en_ZA
dc.identifier.ris TY - Journal Article AU - Thaxter, Chris B AU - Daunt, Francis AU - Grémillet, David AU - Harris, Mike P AU - Benvenuti, Silvano AU - Watanuki, Yutaka AU - Hamer, Keith C AU - Wanless, Sarah AB - Understanding how prey capture rates are influenced by feeding ecology and environmental conditions is fundamental to assessing anthropogenic impacts on marine higher predators. We compared how prey capture rates varied in relation to prey size, prey patch distribution and prey density for two species of alcid, common guillemot ( Uria aalge ) and razorbill ( Alca torda ) during the chick-rearing period. We developed a Monte Carlo approach parameterised with foraging behaviour from bird-borne data loggers, observations of prey fed to chicks, and adult diet from water-offloading, to construct a bio-energetics model. Our primary goal was to estimate prey capture rates, and a secondary aim was to test responses to a set of biologically plausible environmental scenarios. Estimated prey capture rates were 1.5±0.8 items per dive (0.8±0.4 and 1.1±0.6 items per minute foraging and underwater, respectively) for guillemots and 3.7±2.4 items per dive (4.9±3.1 and 7.3±4.0 items per minute foraging and underwater, respectively) for razorbills. Based on species' ecology, diet and flight costs, we predicted that razorbills would be more sensitive to decreases in 0-group sandeel (Ammodytes marinus) length (prediction 1), but guillemots would be more sensitive to prey patches that were more widely spaced (prediction 2), and lower in prey density (prediction 3). Estimated prey capture rates increased non-linearly as 0-group sandeel length declined, with the slope being steeper in razorbills, supporting prediction 1. When prey patches were more dispersed, estimated daily energy expenditure increased by a factor of 3.0 for guillemots and 2.3 for razorbills, suggesting guillemots were more sensitive to patchier prey, supporting prediction 2. However, both species responded similarly to reduced prey density (guillemot expenditure increased by 1.7; razorbill by 1.6), thus not supporting prediction 3. This bio-energetics approach complements other foraging models in predicting likely impacts of environmental change on marine higher predators dependent on species-specific foraging ecologies. DA - 2013 DB - OpenUCT DO - 10.1371/journal.pone.0079915 DP - University of Cape Town J1 - PLoS One LK - https://open.uct.ac.za PB - University of Cape Town PY - 2013 T1 - Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators TI - Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators UR - http://hdl.handle.net/11427/15015 ER - en_ZA
dc.identifier.urihttp://hdl.handle.net/11427/15015
dc.identifier.urihttp://dx.doi.org/10.1371/journal.pone.0079915
dc.identifier.vancouvercitationThaxter CB, Daunt F, Grémillet D, Harris MP, Benvenuti S, Watanuki Y, et al. Modelling the effects of prey size and distribution on prey capture rates of two sympatric marine predators. PLoS One. 2013; http://hdl.handle.net/11427/15015.en_ZA
dc.language.isoengen_ZA
dc.publisherPublic Library of Scienceen_ZA
dc.publisher.departmentPercy FitzPatrick Institute of African Ornithologyen_ZA
dc.publisher.facultyFaculty of Scienceen_ZA
dc.publisher.institutionUniversity of Cape Town
dc.rightsThis is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_ZA
dc.rights.holder© 2013 Thaxter et alen_ZA
dc.rights.urihttp://creativecommons.org/licenses/by/4.0en_ZA
dc.sourcePLoS Oneen_ZA
dc.source.urihttp://journals.plos.org/plosoneen_ZA
dc.subject.otherPredationen_ZA
dc.subject.otherForagingen_ZA
dc.subject.otherTrophic interactionsen_ZA
dc.subject.otherBird flighten_ZA
dc.subject.otherFlight (biology)en_ZA
dc.subject.otherBioenergeticsen_ZA
dc.subject.otherBirdsen_ZA
dc.subject.otherMarine ecologyen_ZA
dc.titleModelling the effects of prey size and distribution on prey capture rates of two sympatric marine predatorsen_ZA
dc.typeJournal Articleen_ZA
uct.type.filetypeText
uct.type.filetypeImage
uct.type.publicationResearchen_ZA
uct.type.resourceArticleen_ZA
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