Ecological study of social organization in the Great Tit, Parus major L.

Abstract

The formation of basic flocks, particularly the movement of the young from dispersal to final settlement in a restricted area, and the factors relating to the association of members in a basic flock are discussed. The field work was carried out in the summer and autumn of 1970 at the Akasaka Palace, Tokyo, Japan. The study area of about 37 ha consisted of mixed evergreen and deciduous broad-leaved forest. In the study area, virtually all of the birds were marked individually by colored rings and their previous history was known. The formation of the basic flocks took place through a successive process; the establishment of summer and autumn ranges of young, and the final association of the young and adults in an area. The young associated with each other to form the summer flock when the family flocks broke up. Most of the young established their summer range within a relatively short period, usually about a month, after becoming independent of their parents. Forming the summer flocks, the young gradually showed a preference for a particular part of their summer range. The number and members of young observed in the same area became more and more constant from this time onward. By the middle of Oct & most of the young established the autumn range within their summer range. The young establish their summer or autumn ranges within the home range of their family flock. The adults remained on or near their previous breeding territory even after the breeding and then the young settled in the area as the autumn range. The home ranges of the adults and the autumn ranges of the young overlapped extensively as a whole. And a basic flock was formed by these birds. The formation of basic flocks is closely related to the period of extensive overlap of home ranges between individuals, and the members of a basic flock are primarily associated with each other by their site attachment.