Studies on the fluctuation of number of Long-tailed Tits along the slopes of the River Tenryu, Nagano (2)

Abstract

1. This paper discusses the seasonal fluctuations of the number and flocking of Aegithalos caudatus trivirgatus along slopes of the River Tenryu, Nagano. It is based on 166 observations made during 1956-60, and, following the first paper (Tori, No. 75, 1960), reports the behaviour of flocks in different divisions of the home range.
2. The study area consisted of 9 divisions, A to H. The 90% of the total number observed occurred in H, 40% in E and F, 20% in A and B, the divisions being closer to human habitation towards A.
3. In division H, flocks were continuously seen with the peak numbers in May and June, while in A and B they occurred from autumn to the next spring, but disappeared during the summer.
4. The flocks tended to move from H to A divisions in their daily, as well as annual behaviours, in the latter the movement having been commenced from September and October.
5. The 30% of the total number observed lived between the divisions A and H, and only 8% of which adhered to A-division-side and the lest towards H.
6. Only 2% of the total number observed remained in the study area for breeding and this may be due to the budding off of small flocks which was noticed several times from autumn to winter.
7. The budding off of small joint flocks towards winter is directed from H to A-divisions. There were also a few movements among them and the last flocks which immigrated into A-H area settled as breeders.
8. In April and May a large joint flock was formed by gradual concentration of family flocks.
9. Pair formation tended to be earlier towards A-division and was delayed towards H, where the breeding was prolonged.