Patterns of connectivity in Citril Finches Serinus citrinella: sympatric wintering of allopatric breeding birds?

Abstract

Capsule Individuals ringed at different localities, where previous analyses detected local genetic and morphological differentiation, overlapped in wintering areas. Aims To analyse winter site fidelity and connectivity in Citril Finches, a species with locally differentiated allopatric breeding populations, but which forms into pairs at the end of the wintering period, when these populations could be sympatric. Methods Analysis based on 238 recoveries obtained from 12 648 birds ringed at alpine localities and 2368 birds ringed at lower-elevation wintering areas in Central Catalonia. Results Citril Finches showed marked winter site fidelity. Birds ringed at different sub-alpine mountain ranges tended to winter in different river basins, but we found some overlap between these sub-populations. Birds from different localities within the same mountain range partly overlapped in wintering areas. Conclusion We found that many Citril Finch sub-populations cohabit during the winter pair formation period, which prompts the question of how Citril Finch populations can maintain local differentiation despite the ample opportunities for gene flow.