Notes on the moult of red-backed shrikes (Lanius collurio) in their non-breeding range

Abstract

Moult data from 302 museum skins and 11 trapped birds from sub-Saharan Africa show the course of flight feather moult. Most birds seem to start flight-feather moult soon after arrival in their southern African non-breeding ranges. About 75% of the birds had started before mid-December, i.e., during the main arrival time of the species. The mode of moult scores 1 and 2 was reached on 7 December; the last birds with a score of zero occurred in the first days of January. The mode of moult scores 5 and 6 was reached on 27 February. Thus, the time elapsed between the days when 50% of the population had reached the first and last stages of recorded moult was about 82 days; nine days later 75% had reached this last stage before moult was completed. Thus, individual moult may be estimated to cover about 80–90 days. The main moulting period is between mid-November and mid-March, thus covering about four months. No temporal difference was detected between males and females. A tendency for an advancement of adults compared to young birds was not statistically significant. According to the progress of the moult, sexing of young birds in the field is possible for 50% of the birds towards the end of January and for most birds before mid-February.