Drivers of intrapopulation variation in resource use in a generalist predator, the macaroni penguin

Horswill, C. , Matthiopoulos, J. , Ratcliffe, N., Green, J. A., Trathan, P. N., McGill, R.A.R. , Phillips, R. A. and O’Connell, T. C. (2016) Drivers of intrapopulation variation in resource use in a generalist predator, the macaroni penguin. Marine Ecology Progress Series, 548, pp. 233-247. (doi: 10.3354/meps11626)

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Abstract

Intrapopulation variation in resource use occurs in many populations of generalist predators with important community and evolutionary implications. One of the hypothesised mechanisms for such widespread variation is ecological opportunity, i.e. resource availability determined by intrinsic constraints and extrinsic conditions. We combined tracking data and stable isotope analysis to examine how breeding constraints and prey conditions influenced intrapopulation variation in resource use among macaroni penguins Eudyptes chrysolophus. Isotopic variation was also examined as a function of breeding success, individual traits and individual specialisation. Variation in isotope ratios was greatest across multiple tissue types when birds were able to undertake mid-range foraging trips (i.e. during incubation and pre-moult). This variation was highly consistent between years that spanned a 3-fold difference in local krill Euphausia superba density and was also highly consistent at the individual level between 2 years that had similar krill densities. However, by comparing our results with previous work on the same population, it appeared that a decrease in local prey availability can increase intrapopulation variation in resource use during periods with more restricted foraging ranges (i.e. during brood-guard and crèche). This study highlights the importance of considering ecological interactions that operate on multiple spatio-temporal scales when examining the drivers of resource use in populations of generalist predators.

Item Type:Articles
Additional Information:"The analysis was funded by a NERC PhD studentship grant number NE/I52797/X, the 2012 fieldwork was funded by the NERC Collaborative Gearing Scheme grant number CGS-76 and the SI analysis was funded by the NERC Life Sciences Mass Spectrometry Facility grant number EK204-14/12"
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Horswill, Dr Catharine and McGill, Dr Rona and Matthiopoulos, Professor Jason
Authors: Horswill, C., Matthiopoulos, J., Ratcliffe, N., Green, J. A., Trathan, P. N., McGill, R.A.R., Phillips, R. A., and O’Connell, T. C.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Marine Ecology Progress Series
Publisher:Inter Research
ISSN:0171-8630
ISSN (Online):1616-1599
Copyright Holders:Copyright © 2016 The Authors
First Published:First published in Marine Ecology Progress Series 548:233-247
Publisher Policy:Reproduced under a Creative Commons License

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