A Study of Life History of Blue Magpie (11)

Abstract

1. During February, 1964 and July, 1972, roosts and roosting hehavior of Blue Magpie Cyanopica cyana were investigated at four different places: Kawanakajima and Karuizawa in Nagano, and Shibuya and Kurume city in Tokyo.2. In autumn to winter, roost trees were chiefly evergreen plants, such as red pine, bamboo and auk, although 'konara' and reed were used early in autumn.3. The heights of roosting trees differed from 2 to 20m, but as already reported, the height did not influence the roosting behavior.4. Dense group of trees was usually selected as roost but in some cases, a single tree near a house was also used, showing a wide roost selection.5. Thus, a roost may be taken in a tree close to house, or along a road with busy traffic, and therefore, the relation with a ditch (for safety) reported in earlier paper may have been a local case.6. Roosts of non-breeding period are continuously used (as reported).7. Earlier and present observations show that the roosting behavior advances as follows: 1) Feeding around 2) Gathering in a tree 3) Flight to roost site 4) Some preroosting celemonial behavior 5) Entering into roost and perch site selection 6) Fall in sleep.8. Behavior in the roost tree advances from selection of sleeping branch, preroosting rest and then to actual sleeping, thus some resting time precedes the sleeping.9. These rather celemonial behaviors were similar between free living birds and those kept in a flying-cage.10. Some factors, such as light intensity, distance from roost, weather and food intake, that may influence roosting behavior were discussed. The lowering light intensity was influential to flock movements directed to the roost and then to actual sleep, but the effect of light intensity rather differed by flocks observed. Within three km from the roost, the distance did not influence the starting time for roosting flight, the strong wind, snow fall, both through coldness, caused earlier roosting time, while the effect of the rate of food intake for the day before roosting was not clear.