SONG VERSUS FOOD - TRADE-OFF DECISIONS IN A BREEDING COLONY OF EUROPEAN STARLINGS STURNUS-VULGARIS

A breeding colony of European Starlings Sturnus vulgaris was observed every morning for a month prior to egg-laying. The whole colony was ei ther involved in singing activity around the nest boxes, or feeding as one big flock in fields. Switches between these 2 activities were sud den and complete with it short intermediate stage when all the birds g athered in a tight group on overhead electricity wires. The switches b etween singing and feeding occurred approximately twice an hour, and l ocal weather conditions had no apparent effect on these switches in be haviour. As egg-laying approached, more time was spent at the nestbox colony, with fewer birds feeding in the fields at any one time. Later in the season longer initial periods were spent at the nestbox colony before the first feeding excursions to the fields, resulting in fewer switches between singing and feeding activities. The switches between the 2 activities also became less distinct nearer egg-laying with the flock breaking up into smaller units and feeding in fields closer to t he nestbox colony.