The response of young Peking ducklings to sibling distress calls

Peking ducklings were tested at 1-2 or 7-8 days of age for their tendency to inhibit their own distress calling in response to the distress calls of siblings. At both ages the ducklings displayed a significant inhibitory response to the sibling calls, although the response of the older birds was greater. When the younger ducklings were subsequently tested with a variety of acoustic stimuli that were similar to the conspecific calls, however, they showed the same degree of response specificity displayed by older ducklings in previous research: in both cases the ducklings more strongly inhibited their vocalizing in response to the sibling calls than to most of these other stimuli. Finally, it was demonstrated that this differential responsiveness to sibling calls was not due merely to differences in pretest exposure to the sibling calls vs these other stimuli. This sensitivity of 1-2-day-old ducklings to sibling distress calls is of interest because (1) this age period is of great importance for the formation of social attachments, including sibling bonds, (2) distress calls are known to play an important role in maintaining family cohesion, and (3) it stands in contrast to the common view that young precocial birds do not respond to sibling distress calls.