Timing and duration of moult in three populations of Purple Sandpipers Calidris maritima with different moult/migration patterns

Abstract

Timing and duration of primary moult in three populations of Purple Sandpipers Calidris maritima were described and discussed in relation to the birds’ need to complete moult before the onset of winter, when resources are required for survival. We predicted that moult would be completed earlier by birds wintering at higher latitudes. The south Norwegian breeding population, which moults and winters along the coast of east Britain (54–57°N) had a mean starting date of 21 July for primary moult (16 July for females and 24 July for males), a mean duration of 61 days, and completed on 20 September. Resident Icelandic (64–65°N) birds had a mean starting date of 22 July for primary moult (17 July for females and 25 July for males), a mean duration of 51 days, and completed on 11 September. Birds moulting in north Norway (70°N) arrived in north Norway in suspended primary moult or without having started moult, and completed it there. They had a mean completion date of 2 November for primary moult (31 October for females and 3 November for males). Starting date and duration could not be estimated because some suspended moult for an undetermined period, but it was thought that they started in late August. It is likely that most originated from Russia. The onset of moult appears to be set by the end of breeding and there is little overlap in these two events. The earlier start of moult by females in all three populations may be because they abandon the males when the chicks hatch, leaving the males to attend the chicks. Although the duration of primary moult followed the expected trend, being fastest in north Norway and slowest in Britain, the onset of moult was so late in north Norway that they had an unexpectedly late completion date, despite their rapid moult. The late completion of primary moult in north Norway suggests that wintering in the far north may not pose the energetic constraints on Purple Sandpipers that had previously been supposed.

Population structure and origins of Purple SandpipersCalidris maritimain north Norway during winter

“…The distribution of bill and wing lengths did, however, appear to be closer to those of the Russian breeding birds, suggesting that most come from here. The timing of primary moult gives an additional clue to breeding origins: in Troms, Purple Sandpipers are late moulters (the average date for completion of primary moult is 2 November: Summers et al 2004). This late moult schedule fits with the late breeding of Russian birds, but not with Svalbard Purple Sandpipers, which start moult and apparently complete moult in September, prior to migrating from Svalbard (Bengtson 1975).…”

Pattern of Wing Moult and Its Relationship to Breeding in the Eurasian Stone-CurlewBurhinus oedicnemus

“…Holmgren et al 2001, Summers et al 2004, Serra et al 2006, but that of the Eurasian Stone-curlew Burhinus oedicnemus (hereafter Stone-curlew) remains poorly known. Indeed, current descriptions regarding this bird (Cramp & Simmons 1983, Ginn & Melville 1983 are based on small sample sizes, and they are not easily comparable to that of other species because they were made well before the latest statistical methodology designed for the analysis of moult data became available (Underhill & Zucchini 1988, Underhill et al 1990).…”

Rapid or slow moult? The choice of a primary moult strategy by immature Wood Sandpipers Tringa glareola in southern Africa

“…Adult migrant waders replace their primaries annually, most commonly on the non-breeding grounds so that they have fresh flight feathers for the return migration and the breeding season (e.g. Prater et al 1977;Ginn and Melville 1983;Summers et al 1989Summers et al , 2004Serra et al 1999;Pearson and Serra 2002;Minton et al 2006). In contrast, juvenile waders use a wide variety of moult patterns.…”