Moult in annual cycle of an alpine songbird — the Alpine Accentor Prunella collaris

The separate scheduling of moult and breeding and of migration in birds that fly long distances between their breeding grounds and wintering areas has been recognized as an ecological adaptation permitting these events to coexist in the annual cycle. The Alpine Accentor Prunella collaris, mountain bird species, lives in harsh and cold alpine conditions. Different breeding schedules and migration strategies of females and males coincide with different moulting patterns between the sexes. Details of moult were obtained from 103 adult birds caught between the July and October (1991–2021) in the Western Carpathians (Slovak National Parks — High Tatras, Low Tatras and Low Fatra). Moult generally lasted from the second decade of July to the first decade of October but mainly during August and September. Mean primary moult duration in this species was calculated to be 36 days. Females had delayed onset of primary moult by about 12 days, of secondary moult by 8 days but moult duration was much shorter in females than in males. Mean duration of primary moult in females was 27 days, in males 43 days. Males moulted primaries over 16 days and secondaries over 10 days longer than females. Females completed primary moult two days and secondary moult one day before males. Migrants — females have adapted to the harsh alpine environment by moulting quickly, while residents — males moult more slowly than females. The alpine lifestyle of accentors leads to significant intersexual differences not only in the timing of breeding cessation, but also in the timing of moulting. This study is the first to provide a more detailed view on moulting in this species as well as discuss its wider ecological impacts on birds' annual cycle considering the alpine ecosystems.