The prebasic moult and basic plumage of female mallards (Anas platyrhynchos)

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Abstract
The prebasic moult and subsequent basic II plumage of immatures and the definitive basic plumage of adult female mallards (Anas platyrhynchos) in late winter were examined from collected birds of known pair status. Female mallards moult into these basic plumages from November to March but an individual completes the prebasic moult in 6–7 weeks; variation among individuals is related to age, pair status, and habitat and weather conditions. The prebasic moult is a complete body moult. Feathers of the crown, facial, neck, upper back, scapular, and flank areas are replaced earlier than feathers in other areas of the body. The basic II and definitive basic plumages are characteristically darker and more sepia than the alternate I and definitive alternate plumages, respectively. The light bands on dorsal feathers are more V-shaped in basic feathers and more sigmoid-shaped in alternate feathers. Colours of the bill and tarsus change to resemble male colouration of these parts during the middle to late portions of the moult. The timing, sequence of feather replacement, and change in plumage aspect of the prebasic moult may reflect adaptations to pressures selecting for reduction of overlapping nutrient requirements of annual cycle events, camouflage, and signaling of pairing status.