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International Journal of Ecology
Volume 2013 (2013), Article ID 737616, 7 pages
http://dx.doi.org/10.1155/2013/737616
Research Article

Winter Latitudinal Population Age-Structure of a Migratory Seagull (Larus fuscus) Differs between Its Two Major Migratory Flyways

1Unidade de Investigação em Eco-Etologia, ISPA, Instituto Universitário, R. Jardim Tabaco, 1149-041 Lisboa, Portugal
2Museu Nacional de História Natural e da Ciência, Universidade de Lisboa, Rua da Escola Politécnica, 58, 1250-102 Lisboa, Portugal
3Biological Sciences Department, Virginia Tech, 800 Drillfield Dr, Blacksburg, VA 24061, USA

Received 19 July 2013; Accepted 1 November 2013

Academic Editor: Jean-Guy Godin

Copyright © 2013 Paulo A. M. Marques and Paulo E. Jorge. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The migration is energy-demanding and is expected to greatly affect the distribution of individuals over the species range and condition the choice of migratory routes. We investigated the wintering distributions and migratory flyways use of geographically contiguous populations of Lesser Black-backed Gulls (Larus fuscus) and difference in population winter age structure between migratory flyways. Recoveries of metal ringed pulli from Denmark, Sweden, and Finland were used. The results showed that contiguous populations can have distinct wintering distribution patterns and migratory flyways. More importantly, we found that depending on the place of origin, the population winter distribution may or may not show a latitudinal cline in the age structure. The population migrating via the eastern Atlantic flyway (western flyway) showed a winter age-related latitudinal cline, with adults staying at more northern latitudes than immatures. In contrast, no such pattern was found in the population migrating along the Mediterranean/Black sea flyway (eastern flyway). Interestingly, immatures within the eastern population showed a more dispersed pattern of migratory bearings. Overall, our results enhance the importance of the migration flyway in shaping the age structure of populations in the winter quarters and how it may influence the effect of other factors like sexual maturation.