Abstract
A decline in bird populations was identified through analysis of audio tape recording data recorded in Karuizawa, central Japan, from 1989 to 2006. Blue-and-white Flycatchers and Jungle Crows populations increased during the study period, however, the populations of most other bird species decreased. Common Pheasants, Common Cuckoos, Oriental Cuckoos, Gray Thrush, Brown Thrush, Bush Warblers, Varied Tits, Siberian Meadow Buntings, Japanese Yellow Buntings and Black-faced Buntings were frequently recorded during the early part of study period, but they disappeared by the end of the period. The timing of the decrease was consistent with increased development in the study area.
