Abstract
The change of nest construction and shape in tit Parus spp. and Tree Sparrow Passer montanus were studied at about 3,000 nest boxes placed at golf courses in Japan. Since 1996, the recorded thickness of tit nest cups, and thickness and shape of Tree Sparrow nests have changed. The ratio of thin-walled tit nests has been increasing over the period from 1996 to 2000. The ratio of unusually open shaped tree sparrow nests rapidly increased in 1998 and 1999, and slightly decreased in 2000 and 2001.
The timing of these nest shape changes coincided with the increased nest box destruction by crows Corvus spp. (also reported by the author in this volume). The change in nest shape may have been a result of les effort spent on nest construction, in an attempt to avoid crow predation.
