SummaryThompson, J. (1990). The sex and age-related distribution of Bar-tailed Godwits in Moreton Bay, Queensland, during the northward migration.Emu90, 169–174.Evidence is presented for the age-related distribution of Bar-tailed Godwits in Moreton Bay, Queensland, during the northward migration in 1989. The age-related distribution was deduced from plumage characteristics, sex ratio patterns and the general distribution of Bar-tailed Godwits in the Bay. A‘natural experiment’at a sewage outfall is described to help explain the age-related distribution. Despite the high densities of birds on the intertidal area adjacent to the outfall, the area appeared to be used by a relatively small proportion of adults. It is suggested that the nature of the intertidal habitat near the sewage outfall is less suited to godwits than island locations in the Bay. Qualitative differences in habitat are suggested to play an important role in determining the overall distribution of Bar-tailed Godwits in Moreton Bay.