Eurasian Tree Sparrow nests observed in old buildings in Hakodate, Hokkaido

Abstract

In Japan, the Eurasian Tree Sparrow, Passer montanus, is common in urban areas and nests in artificial structures. Though frequently described as nesting in old buildings, little has been reported on this behaviour. We estimated the age of buildings and examined whether sparrows were nesting in them or not. We frequently observed sparrows nesting in older buildings and found that they often used spaces in air vents as nest sites.