Photo: Graham Catley
Graham Appleton
Moulting on the move In most northern waders, post-breeding moult is a distinct phase – between autumn migration and the start of winter – but it’s different for Lapwings. Primary moult is one of the key stages of a wader’s life. Knowing the length of the period in which birds are constrained by this energetic process may be really important to our understanding of the whole annual cycle of waders. In Oystercatchers, for instance, it has been shown that in periods of low food abundance they cannot finish their primary moult. One or more of the outer pairs of primaries remain, becoming more faded and worn as the next twelve months pass and providing a signal of a previous period of stress (BTO Research Report No 238).
0 to 5, so an old wing has a score of 0 and a new wing has a score of 50. During the process, there is a gap in the wing, where new feathers are growing. So, a typical bird in mid-moult might have ten feathers scored as 5554332100 (moult score 28), with primary four nearly fully grown and primary eight newly discarded. Unsurprisingly, flight capacity is impeded. It’s not a great time to migrate – unless you happen to be a Lapwing.
For flocks of waders in Britain and Ireland, autumn moult is generally squeezed in between their return from their arctic and sub-arctic breeding grounds and the start of winter, when days get shorter, the weather gets colder and much of the prey becomes less numerous and harder to access. In the late summer, adult birds start to discard the colourful feathers that they grew in spring and the main wing and tail feathers that have served them well for the best part of a year. The key period of moult is the time in which the ten primary feathers are replaced. The inner one (primary 1) on each wing is dropped first and the outer one is last. Each of the ten primary feathers is scored from
Photo: Graham Catley
Time to moult
The shape of a Lapwing’s wing is very different to that of most waders in the UK T H E H A R R I ER – S p r i n g 2 0 1 7
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