Two subspecies are regular migrants, on drained fishponds, alkaline lakes, flooded areas, sedimentation ponds. Migration of the subspecies are well separated in time in spring, in autumn overlaps: Ch. h. hiaticula migrates in March – early April and late July–August, Ch. h. tundrae in late April–May and September–October. Usually, solitary birds or small flocks can be observed. In the peak period in September, rarely more than a hundred individuals can form a loose group.