Differential post-breeding movements of Cetti's Warblers Cettia cetti in two reedbeds in south-west France. Issue 2 (3rd July 2018)

• Record Type: Journal Article
• Authors: Fourcade, Jean-Marc; Fontanilles, Philippe
• Is Part Of: Ringing & migration. Volume 33:Issue 2(2018)
• Page Start: 57
• Page End: 63
• Publication Date: 2018-07-03
• Subjects: Bird banding -- Great Britain -- Periodicals; Birds -- Migration -- Periodicals; Birds -- Great Britain -- Periodicals; Bird banding; Birds; Birds -- Migration; Great Britain; Periodicals; 598.07232
• DOI: 10.1080/03078698.2018.1629115
• Languages: English
• ISSNs: 0307-8698

Abstract

ABSTRACT: Differential post-breeding movements between sex or age groups lead to spatial segregation and can result in the exploitation of different habitats by individuals from the same population. Our aim is to assess whether the use of reedbeds by non-breeding Cetti's Warblers Cettia cetti involves many transients arriving and departing throughout autumn, or a brief dispersal into this habitat after which individuals stay for a prolonged period. We sampled two reedbeds in south-west France: one dry, or flooded by rain, composed of small mixed reeds, and another with tall reeds and influenced by tidal flooding. We analysed daily capture–recapture data in autumn for two years in each reedbed. Capture–recapture analysis did not detect transients and showed a weak transit dynamic, with some immigration, mainly in the first half of September, and negligible emigration. Thus, reedbeds are used by dispersing birds, mostly the same individuals, with at both sites a strong majority of young females. We interpret this segregation as a product of intraspecific competition. We also noted a higher proportion of adult birds in the dry reedbed (27.6%, with equal sex ratio; more similar to habitats used throughout the year) than in the flooded one (11.7%, with 83.3% being females; unsuitable for breeding). These findings have important implications for the significance of reedbed habitat to this species. Its sustained use by young females makes Cetti's Warbler vulnerable to the loss of reedbed, or its degradation due to growth of shrubby vegetation or the lack of suitable management.