Primary moult of adult Red-billed Queleas (Quelea quelea) in southern Africa in relation to patterns of movement

Abstract

The onset and duration of primary moult were investigated for adult Red-billed Queleas (Quelea quelea) in southern Africa. The duration of moult was shortest in Namibia (75 days), intermediate in Botswana (83 days) and longest in Gauteng Province (101 days) and the Eastern Cape (124 days), South Africa. The timing of the onset of moult was similar in Namibia and Botswana (21 and 31 May respectively), but considerably earlier in the Eastern Cape and Gauteng Province (6 and 23 April respectively). Completion of primary moult was well synchronised, ending in August in all sub-regions. Production of feather mass was uniform and speed of moult was controlled by the rate of growth of individual primaries. When moult was faster, fewer feathers grew simultaneously, possibly to reduce the aerodynamic effect of the wing-gap. Red-billed Queleas are thought to migrate relative to the movement of rain fronts, allowing possible multiple breeding events in one season. In southern Africa, Queleas are present throughout their range all year, and a proportion of the population moves short distances in apparently random directions. The large differences in timing and duration of moult in this study only support the short-distance ‘rainfall-migration’ model.