Latitudinal variation of moult annual cycle in West Siberian White Wagtails Motacilla alba dukhunensis Sykes. 1. Post-juvenile moult

摘要

Main parameters of juvenile moult of West Siberian White Wagtails from several areas of West Siberia and the Ural with widely varying latitude are compared. Breeding latitude related variation in the age of moult onset, timing of moult, its extent and rate and its photoperiodic control is shown. On the basis of variation in control patterns of the onset of moult at least two distinct populations adapted to local light-darkness (LD) regimes of high and temperate latitudes are shown to exist in this area. Three groups are distinct in respect to response of moult extent to long days: Yamal tundra birds, lower Ob boreal group and Central Ural group. At least two groups, the Central Ural one and northern ones, differ by their response to short days. No significant latitudinal variation exists between individual moult durations of birds kept at 22L:2D in the Central Ural and at continuous daylight in Voikar, the southern and central Yamal. Northern White Wagtails overlap the end of moult with onset of autumn migration and fattening; the birds from the Central Ural keep these events, especially moult and fattening, separate.