The moult migration

Abstract

The flight- and tail-feathers are shed simultaneously in wildfowl, auks, divers, rails and a number of other groups, thus rendering the birds flightless and rather helpless for a period each year. The birds withdraw at this critical time to special areas where they are safe, usually to secluded places in dense marshes, lakes, coastal waters or the open sea. The main requirements of such areas are sufficient food, safety from predation, and (in water birds) an adequate depth of water. If these conditions are not met on the breeding ground or its immediate vicinity, the birds make a pre-moult shift to areas further away. This has in some cases resulted in a mass transfer of individuals in a fixed direction towards localized moulting places. This so-called 'Moult Migration' is particularly highly developed in wildfowl.