Abstract
Responses in adult and young tree sparrows Passer montanus to the sound of automobile hone were investigated on a feeder in field.
1) The ratio of the number of adults to young visited on the feeder during the experiment was about one to two.
2) The number of sparrows on the feeder just before the horn sounded did not affect on the percentage of the number of sparrows remained on it after horned.
3) Sparrows habituated to the horn sound as the experiment continued. When 3 experimental sessions were carried out in a day, the highest number of sparrows remained on feeder after sounded in the third session.
4) When experiment was resumed on the 12th day after the last experiment, a fewer sparrows remained after the horn sound than in the latest one in the beginning, but more sparrows remained on the feeder soon thereafter.
5) When the horn sounded, adult sparrows were more easily repelled than young ones.
6) The ratio of adult to young sparrows for those first arrived to the feeder after all birds had fled by the horn sound did not differ from the ratio of adults to young visited on feeder under no sound.
7) The more the number of sparrows remained on feeder, the shorter the time taken to increase one more sparrow.
