Experimental Analysis of the Roles of Siblings Calls After Hatching in Chicks (<em>Gallus domesticus</em>): Comparison with an Artificial Auditory Stimulus

Abstract

Several recent studies have emphasized the role of the maternal call in the attachment process in young nidifugous birds. Prenatal auditory stimulation (audition of sibling calls or self perception) is a determinant factor in the development of the attractiveness of the maternal assembly call. However, little is known about the role of sibling calls after hatching. In particular, they may be involved in attraction between broodmates and, in this way, they may compete with the maternal call during the development of attachment. These experiments were designed to test the value of postnatal audition of sibling calls (C). Several groups of chicks were placed in an operant conditioning paradigm in which the instrumental response allowed the birds to receive either auditory, visual or audiovisual stimuli. Results demonstrated that audition of sibling calls is appetitive but, surprisingly, the chicks did not evince a clear-cut choice for this stimulus over audition of a pure tone (T). Moreover, chicks were tested in a choice situation between two audiovisual stimuli. The visual stimulus was the vision of their own image in a mirror (V). In this choice situation between "V + C" and "V + T," chicks did not choose the "V-l-C" stimulus significantly more. Thus, these data, without denying communicative value to sibling calls, support the hypothesis that they do not play an important role in attraction between broodmates and that the main effect of their audition is an activating one. RESUME: Chez le jeune nidifuge, le role du gloussement maternel dans le processus d'attachement filial est bien connu. Plusieurs etudes recentes ont montre que les stimulations auditives survenant durant la periode prenatale (autoperception et audition des cris des autres embryons) constituent un element determinant dans le developpement du caractere attractif de ce gloussement. Peu de choses, cependant, sont connues sur le role des cris des autres jeunes apres I'eclosion. En particulier, il pourraient etre impliques dans les processus d'interattraction entre les jeunes d'une meme couvee. Ceci pourrait done les faire entrer en competition avec le cri maternel au cours du developpement de I'attachement filial. Ces experiences ont ete construites dans le but d'etudier la valeur de ces cris apres I'eclosion. Plusieurs groupes de poussins ont done ete places dans une procedure de conditionnement operant dans laquelle la reponse instrumentale permettait aux sujets d'obtenir, selon les cas, un stimulus visuel, un stimulus auditif ou encore un stimulus audiovisuel.