STUDIES ON THE FLUCTUATION OF NUMBER OF LONG-TAILED TITS (AEGITHALOS CAUDATUS) ALONG THE SLOPES OF THE RIVER TENRYU, NAGANO : (III) THE SEASONAL STRUCTURES OF THE MODE OF LIFE

Abstract

The mode of life of the Long-tailed Tits (Aegithalos caudatus) is discussed bored upon the seasonal fluctuations of the population sizes, range of distribution, and conditions, of dispersion and flocking. The observations were made during 1957-1960 in the area of 1.2 square km along of the River Tenryu, Nagano, and the results were published already. The mode of life may consist of five phases ; winter stability, spring instability, spring stability, summer congregation and autumn instability phases. On the area studied, the Long-tailed Tits are the constant residents and the teritories of its pairs are in the winter home ranges. So that, the winter flocks extend to the peripheral parts of their habitat, and this winter stability phase might have influence on the breeding population and breeding sites. It is observed that the family flocks crowd into the central parts of their habitat during the summer congregation phase. Comparing with other tits of the Paridae, the peculiarities of the Longtailed Tit are found in the summer congregation and the change from the winter stability to the spring stability. It seemed that such phenomena are more similar to gregarious birds of other families rather than to the other species of the Paridae, but the summer large crowding is broken up by the winter flocks during autumn. This mode of life must be compared with the other local populations of the Long-tailed Tits and more other species.