Spring and summer confinement of dark-eyed juncos at autumn migratory destination suppresses normal autumn behaviour

Abstract

A group of dark-eyed juncos, Junco hyemalis, caged during spring and summer on their wintering site of previous years, showed normal spring hyperphagia and fattening, migratory restlessness and post-nuptial moult, but the birds failed to fatten and become normally restless during the ensuing autumn migration season. A second group, treated similarly but not on their individual wintering sites, behaved as the first group except that they did become fat and restless at the appropriate time in autumn. It is probable that perception of the migratory destimation suppressed normal autumn behaviour of the birds held at that destination. Experience may therefore play an important role in the regulation of the avian migratory state.