2009 Volume 5 Pages A1-A8
The tree sparrow Passer montanus is declining in Japan. The explanations so far proposed have not been tested. One possible explanation is that intensive urbanization negatively influences tree sparrow reproductive success. In order to examine this possibility, I compared the number of juveniles, and the number of fledglings cared for by one or two probable parent(s) between urban and rural areas in Kumamoto Prefecture. Results showed that the number of juveniles and the number of fledglings cared for by each pair of tree sparrows were lower in the urban area. These results suggest that tree sparrows suffer from factors affecting breeding success, such as shortages of food (seeds and insects) resulting from urbanization.
