Subspecies-specific features of molt in the common chiffchaff (Phylloscopus collybita L.) from Europe and Western Siberia

Abstract

The patterns of molt in the chiffchaffs of the nominotypical subspecies from central Europe and eastern European subspecies from the Ladoga region are compared with that of the Siberian subspecies from the lower Ob region. The onset dates of postjuvenile molt in the Siberian subspecies are controlled endogenously, while in the nominative and, probably, eastern European subspecies they are under photoperiodic control. The molt of chiffchaffs from central Europe is no less complete than in birds from the Ladoga region and more complete than in Siberian birds. The individual duration of molt is the shortest in Siberian birds and the longest in central European birds, being intermediate in birds from the Ladoga region. Differences in the pattern of postnuptial molt between chiffchaffs from the Ladoga and Ob regions concern its duration and completeness. The completeness of molt proved to be reduced in half of examined birds from the Ladoga region and in some birds from the Ob region. The duration of complete molt in birds from the Ob region is smaller (40 days vs. 60 days in birds from the Ladoga region) at a longer daylight period, which is evidence for a higher rate of feather growth. The completeness and timing of prenuptial molt do not differ between the subspecies.