Special moult of breast and belly feathers during breeding in Golden Plovers<i> Pluvialis apricaria</i>

Samples of breast feathers of Golden Plovers were collected from live birds captured in spring and autumn staging areas in The Netherlands. Three types of feathers were distinguished: winter and summer feathers, and a peculiar type, called the striped feather. Striped feathers were not found in spring, but made up about 20% of the feathers in samples collected in autumn. Examination of skins of birds collected on the breeding grounds showed that striped feathers develop on the breast and belly of Golden Plovers around the last week of incubation. After arrival in The Netherlands, striped as well as summer feathers are replaced by winter feathers (post-breeding moult). The moult, on the breeding grounds, of part of the ventral summer plumage to special (short-lasting) striped feathers is named the partial breeding moult, and appears hitherto undescribed in other birds. The appearance of striped feathers makes the summer plumage of Golden Plovers less contrasting. This leads us to propose that the balance between selection for a distinctive plumage and for camouflage changes in the course of the season and has thus lead to the evolution of this peculiar moult