Analysis of mixed flocks of tits in the botanical garden of Tôhoku University, Sendai

II. Foraging layers by species and their interrelations within the mixed flock

Abstract

1. Observations of mixed flocks of tits were made during 1962 and 1963, at the Botanical Garden of Tôhoku University in Sendai. The foraging layers by species composing mixed flocks and their mutual correlations were especially noticed and it was found that presence or absence of Long-tailed Tit Aegithalos caudatus trivirgatus affected the flock behavior of other species.
2. Similar results were obtained in the different habitat, Kagitori district near the Botanical Garden. In both habitats, floral analyses and measurements of forest layers were made.
3. The preferred foraging layers differed significantly by four species of tits. Long-tailed Tit and Willow Tit Parus atricapillus (montanus) restrictus foraged principally within the lower conifers and the upper part of deciduous trees, in which vegetational cover was dense.
4. Long-tailed Tit and Great Tit Parus major minor showed a marked seasonal change in foraging height. Only the Great Tit is the ground feeder at least in late fall and winter. Coal Tit Parus ater insularis is found in the upper part of the conifer.
5. The foraging layer of a species differed in mixed flocks with or without the Long-tailed Tit. When with Long-tailed Tit, the Great and Coal Tits were attracted by the Long-tailed, and when without it, the Great and Willow Tits were attracted by the Coal Tit and followed it. There were same relationships in Kagitori habitat.
6. It was suggested that by forming a mixed flock, each species, except Long-tailed Tit, would have advantage to forage in wider range of forest layers, attracted by and following the the leading species.