Changes in singing activity of birds at four forest sites of Japan based on long-term monitoring through Cyberforest live sound transmission

Abstract

We recorded avifauna by listening to live sound broadcasts from Furano, Hokkaido; Chichibu, Saitama; Yamanakako, Yamanashi; and Shiga Kogen, Nagano Prefectures during three months of the breeding season from 2012 to 2024. Of the 81 major bird species, 65 showed no significant trend of increase or decrease. On the other hand, 11 species, such as Varied Tit Sittiparus varius and Eastern Crowned-warbler Phylloscopus coronatus, increased significantly, and five species, such as Japanese Tit Parus cinereus, decreased significantly. In Chichibu, the Community Temperature Index increased over the 12 years, indicating a change to the bird community of a warmer region, while other sites showed no significant changes. Other studies have also shown an increase in the species richness of mainly broad-leaved forests, such as Varied Tit and White-eye Zosterops japonicus, at study sites in central Honshu at elevations similar to Chichibu, suggesting that a significant change in avifauna is currently occurring at elevations about 1000 m in central Honshu.