2023 Volume 72 Issue 2 Pages 195-210
In Obata Ryokuchi Park, Nagoya City, mixed-species flocks typically include five species: Japanese White-eye Zosterops japonicus, Long-tailed Tit Aegithalos caudatus, Japanese Tit Parus minor, Varied Tit Poecile varius, and Japanese Pygmy Woodpecker Dendrocopos kizuki. While there have been many studies of Long-tailed Tit in heterospecific flocks, there have been few studies of Japanese White-eye, and their role (as flock leaders or flock followers) is not known. We aimed to elucidate Japanese White-eye's role in heterospecific flocks by examining flock structure, changes in behavioral allocation, and responses to playback experiments using the calls of the five species that compose the flocks. Two types of mixed-species flocks were observed at the study site, one consisting mainly of Long-tailed Tit, and one consisting mainly of Japanese White-eye. When in heterospecific flocks, Japanese White-eye reduced their time spent in vigilance behaviour. In playback experiments, Long-tailed Tit was only attracted to calls of conspecifics, whereas Japanese White-eye and the three other species were attracted to calls of Long-tailed Tit. Accordingly, we have revealed that Japanese White-eye behaved as a passive nuclear species in heterospecific flocks not including Long-tailed Tit, but otherwise acted as an active nuclear species.
