Distress calling as a function of group size in newly hatched ducklings.

Abstract

Khaki Campbell ducklings were raised in groups of 10, 6, and 3 subjects for 1 week. When the groups were intact, the birds seldom emitted distress calls. When, however, various numbers of birds were systematically removed from each of the groups, the fewer the number of birds remaining in a given group the greater the number of distress calls. Further, a given number of birds remaining from a large group emitted more distress calls than when the same number of birds remained from a smaller group. Subsequent experiments revealed that neither adding birds to a group nor interchanging birds between groups induced distress calling; hence, the distress calling induced by reduction in group size was not simply a reaction to stimulus change. Finally, when ducklings that had been living in a group of a given size were permitted to live in a larger or smaller group for more than 24 hours, they subsequently reacted to reductions of their new group in the same manner as ducklings that had lived in a group of that size all along. These findings are consistent with naturalistic observations of the reactions of immature precocial birds to changes in the composition of their brood.Laboratory studies of imprinting and attachment have typically focused on dyadic relationships: the interactions between a young animal and its mother (or mother surrogate) or the interactions between two peers. Though there are clear advantages to such an experimental strategy, there are reasons to suspect that this approach causes one to miss much of the richness of an animal's social interactions. In a natural setting a young animal typically interacts both with its mother and with a group of conspecifics. A number of investigators (e.g., Harlow & Harlow, 1969;Lorenz, 1935) have shown that an animal's social and emotional development is affected by numerous social inputs.

Distress calling induced by reductions in group size in ducklings reared with conspecifics or imprinting stimuli

“…Those studies also revealed that a single imprinting stimulus was equivalent to several ducklings in terms of its effectiveness in suppressing distress calls. results for the conspecific-condition ducklings replicate previous research from our laboratory (Gaioni et al, 1977). Second, the birds in Experiment 1 were reared in groups that were the same size as those in which the conspecific birds of Experiment 2 were reared, but they were tested with virtually the same procedure as that used in Experiment 3.…”

“…Under both conditions, the fewer the number of other birds present, the more distress calls the bird(s) gave. This closely replicates our previous research (Gaioni et al, 1977(Gaioni et al, , 1980. The advantage of the companion-bird technique is that it allows the measurement of distress calling in individual ducklings.…”

“…Prior research (Gaioni et al, 1977) had revealed no differences between the distress calling of those birds moved to the second test box and the calling of the birds that remained in the first box.…”

“…Gaioni. Requests for reprints should be sent to Stephen J. Gaioni maining birds will give (Gaioni et al, 1977). This sensitivity to changes in brood size does not depend on particular birds being present.…”

“…Very little attention has been focused on sibling attachments (Shapiro, 1980). We have begun examining sibling interactions within the context of duckling perception of brood size (Gaioni, DePaulo, & Hoffman, 1980;Gaioni, Hoffman, Klein, & DePaulo, 1977). Ducklings reared in a brood of a given size adapt to that size such that they will give distress vocalizations if the number of birds in the brood is reduced substantially.…”