抄録
I have been banding Tree Sparrows, Passer montanus, at Ueno Zoological Gardens from 1977 to 1991. 427 Tree Sparrows (152 nestlings, 182 juveniles, 93 adults) were banded during this time. Of the 334 nestlings and juveniles, 6 returned and were recovered at their birth-place. I presume that food abundant at this banding site (the West Garden: about 2 ha) and that it also has numerous nesting and roosting places, so that the adult survival rate is high. Therefore, most juveniles disperse from the area. However, there was little difference in juvenile return rates between present study and other studies conducted at snowy regions of Japan. In the future, I will investigate factors influencing juvenile return rates.
