The annual cycle of sixAcrocephaluswarblers in a Nigerian reed-bed

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Abstract
Three Afrotropical species and 3 Palaeartic migrant species of Acrocepalus warblers [A. schoenobaenus, A. scirpaceus, A. arundinaceus, A. baeticatus, A. rufescens and A. gracilirostris] inhabit a reed-bed at the Jekara dam, Kano, northern Nigeria. A study of their seasonal occurrence and weight changes was made by mist-netting during 1981-82. Individuals of the Palaeartic species comprised about 85% of the total captures of Acrocephalus during the period September to May. The Sedge Warbler was the commonest species throughout this time. Reed Warblers appeared in November, numbers increased steadily to March and April, and the last birds were seen in May. Both Sedge and Reed Warblers grew fat in March-May at rates of perhaps about 0.3 g/day. A few Great Reed Warblers were caught during the months October-December and March-May. Their weights were considerably higher in spring than in autumn. Individuals of all 3 of the Palaearctic species were recaptured at the same site in the following season. The Afrotropical species, the African Reed Warbler, the Lesser Swamp Warbler and the Rofous Swamp Warbler, were apparently present throughout the year. There was some evidence of a common breeding season, beginning in April-May. All 6 species probably moult mainly in October to December.