Provenance does matter: links between winter trophic segregation and the migratory origins of European robins

Catry, P., Campos, A. R., Granadeiro, J. P., Neto, J. M., Ramos, J., Newton, J. and Bearhop, S. (2016) Provenance does matter: links between winter trophic segregation and the migratory origins of European robins. Oecologia, 182(4), pp. 985-994. (doi:10.1007/s00442-016-3725-z) (PMID:27638183)

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Abstract

Amongst migratory species, it is common to find individuals from different populations or geographical origins sharing staging or wintering areas. Given their differing life histories, ecological theory would predict that the different groups of individuals should exhibit some level of niche segregation. This has rarely been investigated because of the difficulty in assigning migrating individuals to breeding areas. Here, we start by documenting a broad geographical gradient of hydrogen isotopes (δ2H) in robin Erithacus rubecula feathers across Europe. We then use δ2H, as well as wing-tip shape, as surrogates for broad migratory origin of birds wintering in Iberia, to investigate the ecological segregation of populations. Wintering robins of different sexes, ages and body sizes are known to segregate between habitats in Iberia. This has been attributed to the despotic exclusion of inferior competitors from the best patches by dominant individuals. We find no segregation between habitats in relation to δ2H in feathers, or to wing-tip shape, which suggests that no major asymmetries in competitive ability exist between migrant robins of different origins. Trophic level (inferred from nitrogen isotopes in blood) correlated both with δ2H in feathers and with wing-tip shape, showing that individuals from different geographic origins display a degree of ecological segregation in shared winter quarters. Isotopic mixing models indicate that wintering birds originating from more northerly populations consume more invertebrates. Our multi-scale study suggests that trophic-niche segregation may result from specializations (arising in the population-specific breeding areas) that are transported by the migrants into the shared wintering grounds.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Newton, Dr Jason
Authors: Catry, P., Campos, A. R., Granadeiro, J. P., Neto, J. M., Ramos, J., Newton, J., and Bearhop, S.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Oecologia
Publisher:Springer
ISSN:0029-8549
ISSN (Online):1432-1939
Published Online:16 September 2016
Copyright Holders:Copyright © 2016 Springer-Verlag Berlin Heidelberg
First Published:First published in Oecologia 182(4):985-994
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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