Adpatation for acoustic information through the environment : importance of duration parameters in the distress calls of the starling (Sturnus vulgaris)

According to information theory, the extension of the duration parameters of acoustic signals increases their efficacity. The aim of our study was to test this hypothesis on distress call of a bird, the starling Sturnus vulgaris. Distress calls are high intensity alarm signals produced by birds when they are seized by a predator. Earlier studies revealed that frequency modulation constitutes an important feature of distress calls for triggering responses. The coding-decoding process is thus precisely defined. On the contrary, the coding of duration parameters seems imprecise since individuals produce distress calls of variable lengt