Abstract

The Red-necked Stint Calidris ruficollis breeds in the northern hemisphere and migrates to southern latitudes for its non-breeding period where adults undergo a complete moult of the flight feathers. Juveniles follow the adults to the wintering grounds but remain for the breeding season, the southern winter, and do not moult all their flight feathers until the following year. Returning adults and second-year birds begin to moult their primaries between late August and early December and finish between late December and late March. The mean duration of moult of their primaries is calculated as 130 days, fifteen days longer than that previously reported. Previous authors may not have distinguished non-moulting first-year birds and the inaccuracies in their method of calculation probably account for the difference. Distributions of the moult scores of the primaries of the adults are unimodal and we dispel Evans's (1975) suggestion of subgroups. Pooling of data from separate samples, asymmetry between the wings during early stages of moult, decrease in the rate d moult in middle to late stages and possible bias in sampling all may have contributed to the artificial formation of subgroups.