Structure of flock range in the Long-tailed Tit

1. Winter flock, its home range and territory

Abstract

1. The home range, structure, distribution and function of the winter flocks of Long-tailed Tit Aegithalos caudatus were studied in three winters during 1965-1968, in a mixedwood of Quercus serrata, Larix leptolepis and Pinus densiflora at footzone of middle Honshu.
2. Using the census methods of observation-mapping, trace-mapping and time-mapping, 243 winter flocks were recorded on the field map, and activity loci, center of activity radii, activity densities, pattern of movement and fighting behaviors were analyzed.
3. Winter fiock-size ranged from 3 to 15 (average 7.6) birds and they were most frequently encountered during November and January.
4. A flock range consists of the following three components: 1. Basic space. The core of home ringe, with the radius of 200 meters and having high activity density. The 80% of the whole day activity is spent in here, including the places for foraging, bathing, and snow-bathing. 2. Wandering spaces. They radiate from the basic space, two of which may extend as long main wandering courses. They have functional relation to stability of the fiock, 3. Peripheral space. Surrounding area where flock ranges may be overlapped and fightings for defense occur between flocks.
5. The form of home range of the flock is oval, the long axis stretching along a small valley and the short axis compressed between ridges. The social stability of a flock is maintained under such topographical factors.
6. The range of flock activity can be regarded as flock-territory, since it is defended by the flock as a unit. Exchange of flock members seldom occurs and the flock range do not change through the winter nor through the life of an individual. The defenese between adjoining fiocks is evident.
7. In an uniform mixed wood the activity range of a flock is about 0.2km². It is not subject to the flock-size but to the area of available habitat. The flock never increases to a great size. Thus, the local populations of the Long-tailed Tit are regulated by flock territoriality which has density-dependent function. The size of winter fiocks and their range-size control the population and distribution range of the breeding pairs.