Ageing Cetti's Warbler Cettia cetti by means of plumage characteristics

Abstract

This paper presents a new and reliable ageing criterion for Cetti's Warbler Cettia cetti. The method is based on the knowledge of the extent and pattern of post-juvenile moult and the differences in colour and pattern between juvenile and adult feathers. The greater coverts and the innermost remiges appear to be the most useful feather tracts for determining age. © 1997 British Trust for Ornithology.