La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Methods for ageing Dotterel Charadrius morinellus
Auteurs :	D. Philip Whitfield, Auteur
Type de document :	Article
Dans :	Ringing & Migration (19(3) May, 1999)
Article en page(s) :	200-204
Résumé :	This study compared two methods of ageing Dotterel, the 'standard' method that separates first-years from older birds (adults) on primary tip wear and presence/absence of juvenile inner median coverts, and the 'growth bar' method that assumes first-years have the same growth bar pattern across rectrices whilst in adults the pattern differs across rectrices. The comparisons involved museum skins and live birds breeding in the Scottish Highlands. The standard method was robust: ageing on primary tip wear and inner coverts gave the same results, known-age colour-ringed birds were aged correctly and estimates of the percentage of first-year birds in the breeding population were consistent with expectations from other population parameters. By contrast, the growth bar method had flawed assumptions, incorrectly aged some birds and produced a relatively high estimate of the percentage of first-year birds in the breeding population that was probably inaccurate. With the existence of apparentlyaccurate ageing criteria under the standard method, it is concluded that there is no justification for using the growth bar method, even as a supplementary technique.

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