A study of the life history of Blue Magpie 4

Flock movements

Abstract

1. During August 1962 and December 1965, field observations of the Blue Magpie Cyanopica cyana were made in three localities in Nagano and one place in Tokyo. The daily routine of flock movements, seasonal change of activity and the time spent at various environments along the daily routes, were chiefly studied.
2. The length of daily activity time was average 60% of the day (24 hours) in family flocks and 45% in local area flocks. It also changed with the seasonal day length.
3. The family flock took a simple fixed route of movement, while the local area flocks traced a very complicated course, taking different directions in an irregular way and finally returned to or near the fixed roost.
4. Each family flock never mixed its young birds with each other. The leader of a flock was not recognized, and the flock's route changed when there was predator including men.
5. It was postulated that flock makes an evaluation of environment, changing the staying time and moving speed according to different local conditions.
6. A local flock may move 3.5-5.0km a day, with the speed of 340-520m/h and the difference by morning and afternoon was irregular.
7. A local flock moved 10-17 ha per day, which was 34-60% of the total daily activity range. This range covered 0.65-0.85km east to west and 0.7-0.8km north to south.
8. The dispersion density within a total daily activity range was 0.6-1.9 bird/ha.