Moult, ageing and sexing of kestrels

Abstract

An examination of 44 Kestrel skins and some 250 trapped Kestrels showed that: (a) wing moult started in mid-May or early June and finished in early September, (b) Tail moult started some two weeks later, but finished at approximately the same time as wing moult, (c) Juveniles could be reliably distinguished from adults by the size of the buff tip on the innermost primary, or by the markings on the flank feathers, (d) The colour of the head, rump, upper tail coverts or tail were a poor guide in sexing juveniles, which could only reliably be sexed using the adult feathers they gradually acquired during their first winter. © 1980 Taylor & Francis Group, LLC.