FEEDING ECOLOGY OF TITS, WITH NOTES ON TREECREEPER AND GOLDCREST.

Abstract

SUMMARY The feeding habits of the titmice, Treecreeper and Goldcrest were studied in a mixed broad‐leaved wood near Oxford, from April 1950 to August 1951, by means of repeated standard observations. The proportion of time spent feeding varied inversely with the body‐weight of the species. A greater proportion of the time was spent feeding in mid‐winter, and in the breeding season when young were being fed, than in spring or autumn. Feeding intensity varied similarly. Fighting for food was recorded most often in mid‐winter, and rarely in summer. Most attacks were intraspecific. Probably individuals gain or lose much food by fighting. Although adult birds search for food most of the time when feeding young, they preen then as often as at other times. The period and intensity of singing and calling was measured. This was often performed concurrently with other activities–mainly feeding–in the tits, least often by Great Tits, most often by Coal Tits. Distant flight was more often recorded in winter than in summer. The frequency with which the birds fed (a) in different species of trees and shrubs, and (6) at different feeding stations, varied significantly from month to month. The behaviour of the birds is described. The Parus species fed most diversely in autumn, and least diversely in early summer. Coal and Marsh Tits fed more diversely than Great and Blue Tits, which in turn fed more diversely than Longtailed Tits and Goldcrests. The tit species were more distinctly segregated from each other by feeding habit in winter than in summer. Food was especially short in mid‐winter and in the breeding season, and competition for food was most severe in mid‐winter. Hence mortality from food shortage is probably more density‐dependent in winter than in summer. Although the several tit species have much in common, and often eat the same foods, each species has evolved characteristic methods of feeding, with corresponding structural adaptations; and each species occupies a more or less distinct feeding‐niche.