Aversive Response of Tree Sparrows Passer montanus to Distress Call and the Sound of Paper Flag

Abstract

The response of tree sparrows, Passer montanus, to the distress call of its own species (DC) was compared with their response to the sound produced by a paper flag (FS) and their response to another noise (NS) in both laboratory and field settings. When these sounds were presented to young sparrows in a cage in the laboratory, FS evoked higher active movement than DC did, and NS produced the lowest movement. Repeated presentations of the same sounds and the order in which each sound was presented had no effects on the sparrow movement. When FS was played repeatedly at a longer interval, the intensity of response of birds decreased. When DC and FS were played back to the flock of sparrows assembling at a feeder, almost all individuals flew away, but the number remaining without flying increased gradually as trials progressed. The mean number of sparrows present 3 min after a playback was smaller for FS than for DC. The habituation rate in the former was also slower than in the latter. These results show that FS, which has a non-biological origin, induces a stronger aversive response by tree sparrows than their own natural distress call.