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Golden plovers Pluvialis apricaria moulting on nest in Swedish Lapland |
| For readers from other continents: The Golden Plover Pluvialis apricaria has a restricted north-west Palearctic distribution. All populations, from the Arctic to W Europe, seem to initiate their moult while brooding. |
Voous (1960) characterized the Golden Plover, Pluvialis apricaria, as a "probably not very successful (read: in terms of absolute population) northeast Atlantic isolation product of the circumpolarly distributed group of golden plovers". On high mountain heath in Swedish Lapland it is one of the most robust inhabitants, however, as well-adapted to the wet and chilly weather as another northeast Atlantic evolutionary "product", the arctic birch Betula pubescens tortuosa forming the upper limit of subalpine forest in the same area. The particular strength of the Golden Plover seems to lie in its elliptic, compact body form, that minimizes energy losses and allows the bird to weather frost, prolonged rainfall and even snow-cover during the breeding season. In addition there is a distinct division of labour between sexes when eggs are brooded (e.g Steiniger 1959), the "free" bird often foraging far away from the nesting territory. This in turn may be the reason why adults are even capable of initiating their moult during the same period. Three breeding birds from the Tjålmejaure area, c. 66.15 N, 16.10 E, Pite Lappmark, and three from the Leavasjokka area, Torne lappmark, investigated 1998 - 2000, clearly demonstrate this fact:
According to Stresemann & Stresemann (1966), Icelandic breeding birds will start moulting already in late May or early June, shortly after egg-laying, and migrate with fresh primaries to W Europe between September and November. Golden Plovers investigated in Germany in August and September (most likely of Scandinavian and Russian origin) had the typical wader pattern with inner primaries fresh (like migrating Dunlin); either they had started moulting on breeding grounds and suspended, or they had simply migrated with growing wing. Ginn & Melville (1983) mention a Welsh bird with Pscore 7 on 6 June.
Henriksen (1985) analysed a very large material (n=1263) of Golden Plovers, shot in Denmark after 1 August; wings of the birds were sent as verification to Vildtbiologisk station, Kalö. In addition skins from Scandinavian breeding-grounds May - July were investigated. Only 15 birds shot had growing primaries in the sections P1 - P4 or P2 - P5, while 9 of the birds from breeding-grounds moulted inner primaries (Pscore 0 - 20). Henriksen points out that both Lapwing Vanellus vanellus (Beser 1972, Hansen 1979) and Grey Plover Pluvialis squatarola (Branson & Minton 1976) often have P1 - 5 or 6 growing simultaneously, and suggests that the slower rate of growth in Golden Plovers is an adaptation to the fact that these birds start moulting while still breeding.
In fact the Lapland birds start while still brooding, and in no case more than three primaries have been growing simultaneously. But, given the early start, there is still time for them to exchange six or seven primaries before migrating, so the general Charadrii pattern still holds in birds from Lapland. On the other hand there may be differences between years; breeding was retarded at Tjålmejaure in 1998 and very advanced at Leavasjokka in 2000. In normal years Golden Plovers from Lapland will shed one or two inner primaries in the first half of June, just like birds from Iceland and W. Europe.
The moult cards were recorded by Peter Olsson and Christer Persson, this note first published on the web on 31.10.98, new material added 8.8.00.