Song versus food: trade-off decisions in a breeding colony of European StarlingsSturnus vulgaris

A breeding colony of European Starlings Sturnus vulgaris¸ was observed every morning for a month prior to egg-laying. The whole colony was either involved in singing activity around the nestboxes, or feeding as one big flock in fields. Switches between these 2 activities were sudden and complete with a short intermediate stage when all the birds gathered in a tight group on overhead electricity wires. The switches between singing and feeding occurred approximately twice an hour, and local weather conditions had no apparent effect on these switches in behaviour. 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...