Age Determination in the Bull-headed Shrike Lanius bucephalus based on Buff-tips of Greater Primary Coverts

Abstract

A total of 197 Bull-headed Shrikes Lanius bucephalus were examined for this study. Out of 756 nestlings banded for a population study, 38 were re-captured more than once and examined. Their plumage was checked for the presence of buff-tipped greater primary upper coverts (BTGPUCs), and the process of replacement of the buff-tipped coverts was followed. Similar examinations of BTGPUCs were also made on 6 juveniles and on 153 other captured birds whose age could not be established. At least some proximal juvenal BTGPUCs, almost without exception, were retained until the second fall molt. Thus, the presence of these juvenal feathers in the greater primary upper covert (GPUC) series is a reliable criterion for designating first-year birds in this species.