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Site fidelity and individual variation in winter location in partially migratory European shags

Grist, Hannah; Daunt, Francis; Wanless, Sarah; Nelson, Emily J.; Harris, Mike P.; Newell, Mark; Burthe, Sarah; Reid, Jane M.. 2014 Site fidelity and individual variation in winter location in partially migratory European shags. PLoS ONE, 9 (6), e98562. 14, pp. 10.1371/journal.pone.0098562

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Abstract/Summary

In partially migratory populations, individuals from a single breeding area experience a range of environments during the non-breeding season. If individuals show high within- and among- year fidelity to specific locations, any annual environmental effect on individual life histories could be reinforced, causing substantial demographic heterogeneity. Quantifying within- and among- individual variation and repeatability in non-breeding season location is therefore key to predicting broad-scale environmental impacts on the dynamics of partially migratory populations. We used field resightings of colour-ringed adult European shags known to have bred on the Isle of May, Scotland, to quantify individual variation and repeatability in winter location within and among three consecutive winters. In total, 3797 resightings of 882 individuals were recorded over 622km of coastline, including the Isle of May. These individuals comprised over 50% of the known breeding population, and encompassed representative distributions of ages and sexes. The distances from the Isle of May at which individuals were resighted during winter varied substantially, up to 486km and 136km north and south respectively and including the breeding colony on the Isle of May. However, resighting distances were highly repeatable within individuals; within- and among-winter repeatabilities were >0.72 and >0.59 respectively across the full September-March observation period, and >0.95 and >0.79 respectively across more restricted mid-winter periods. Repeatability did not differ significantly between males and females or among different age classes, either within or among winters. These data demonstrate that the focal shag population is partially migratory, and moreover that individuals show highly repeatable variation in winter location and hence migration strategy across consecutive winters. Such high among-individual variation and within-individual repeatability, both within and among winters, could lead to substantial life history variation, and therefore influence population dynamics and future conservation management strategies.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1371/journal.pone.0098562
Programmes: CEH Topics & Objectives 2009 - 2012 > Biodiversity > BD Topic 1 - Observations, Patterns, and Predictions for Biodiversity > BD - 1.4 - Quantify and model interactions to determine impacts ...
CEH Sections: CEH fellows
Watt
ISSN: 1932-6203
Additional Information. Not used in RCUK Gateway to Research.: Open Access paper - Official URL link provides full text
NORA Subject Terms: Ecology and Environment
Marine Sciences
Zoology
Date made live: 01 Jul 2014 09:46 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/507595

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