The Willow Warbler Phylloscopus trochilus is one of the few bird species that undergoes two primary moults a year, a post‐nuptial moult in the breeding area and a moult in the wintering area. Primary‐moult data for Willow Warblers from Finland, Sweden, Britain, the Netherlands, Belgium. Guinea‐Bissau, Uganda, Kenya, Malawi, Zambia, Zimbabwe, Botswana and South Africa are analysed. The parameters of primary moult (mean starting date, standard deviation of starting date, and duration) are estimated using the techniques of Underhill & Zucchini (T.988 Ibis 130: 358–372) and Underhill, Zucchini & Summers (1990 Ibis 132: 118‐12 3). The scheduling of moult in relation to theother main components of the annual cycle, breeding and migration, is considered. The mean durations of post‐nuptial moult for P. t. trochilus and P. t. acredula are 36.5 and 38.3 days, respectively; the start and termination of moult for P. t. trochilus are about 3.5 days later for each degree of latitude northwards, and the start and termination of moult for P. t. acredula, are about 10 days later than that of the most northerly populations of P. t. trochilus studied. Females start their postnuptial moult about 10 days later than males. Southward migration commences as soon as post‐nuptial moult is complete. There is an increasing constraint on the timing of breeding and post‐nuptial moult events at higher latitudes, leading to overlap between them. The duration of pre‐nuptial moult is longer than that of post‐nuptial moult, and is completed shortly prior to northward migration.

Extended primary moult as an adaptation of adult Wood Sandpipers Tringa glareola to their freshwater habitats in southern Africa. Ardea 97(3): 271-280.Migrant waders using freshwater habitats are hypothesized to have slower primary moult than waders using coastal habitats. We chose the Wood Sandpiper Tringa glareola as a representative species using the freshwater habitats and compare its moult pattern with a range of fresh-water and coastal wader species to test the habitat hypothesis. Only fragmentary descriptions of Wood Sandpipers' primary moult in their sub-Saharan non-breeding quarters had existed. We analysed the primary moult formulae of 1496 adult Wood Sandpipers obtained in southern Africa. The Underhill & Zucchini moult model was used to estimate the timing and duration of moult for all 10 primaries combined and for each primary individually. We also estimated the rate of production of feather material during moult. Adult Wood Sandpipers arrive in southern Africa between late July and November, and depart from mid-March to April. Suspension of moult was observed in 56 birds (7.5%) after two to nine primaries had been replaced. The remaining birds performed a continuous complete primary moult, with average start and completion dates of 21 August and 30 December, respectively; estimated duration was 131 days. The overall rate of production of primary feather material was uniform, achieved by growing up to five small inner primaries simultaneously at the beginning of the moult but only one or two simultaneously while the large outer primaries were growing. Primary moult of adult Wood Sandpipers took longer but ended earlier than in similar-sized waders using coastal habitats. Compared with waders using coastal habitats, Wood Sandpipers prolonged moult by shedding their primaries at longer intervals and by extending the growth period of each primary. The longer primary moult and its earlier ending compared with coastal waders are probably adaptations to Wood Sandpipers' use of freshwater habitats, which in southern Africa provide unpredictable food supplies and might require nomadic movements between ephemeral inland wetlands.

Immature migrant waders have more complex patterns of primary moult than adults, but these have been described only fragmentarily. The Wood Sandpiper Tringa glareola breeds in the taiga region of the Palearctic and part of the population migrates to southern Africa. We selected this population for a study of the primary moult strategies of an immature wader. After analysing the moult formulae of 674 immatures, we discuss potential factors that influence the choice of moult strategy. All moulters replaced two to six outer primaries; 91% moulted four or five. We used the Underhill-Zucchini model to estimate the timing and duration of moult in immatures replacing different numbers of primaries. A slow moult of five or six primaries, adopted by 29%, lasted on average 98-111 days, beginning on average 8-16 December. Moult of four primaries (63%) began on 6 January and averaged 73 days. A rapid moult of three primaries (7%) began on 24 January and averaged 55 days. All groups ended their moult between 19 and 28 March. GLM models showed that heavier immatures were more likely to start moulting than leaner birds. This tendency was more pronounced in November-January than in later months. The later the moult started, the fewer feathers were replaced and the faster the process. Departure time set the limit for the end of moult. We suggest the ability to choose different strategies allows immature Wood Sandpipers to adjust their moult to the variable conditions they encounter at wetlands in southern Africa.

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