Selective Control of Peep Vocalizations By Familiar Sound in Young Coturnix Quail

Abstract

Two experiments were designed to examine the hypothesis that young Coturnix quail can learn to peep selectively to familiar sounds soon after hatching. The possibility that the presence of a familiar visual stimulus during training is necessary for effective post hatch learning, as has been reported for several other species, was also considered. Experimental quail were exposed to brief repetitive sequences of 700 Hz or 900 Hz tones alternating with equal periods of silence for a total of 80 min. Chicks were exposed either alone or in groups, and cither with or without a familiar visual object. Controls were not exposed to either sound stimulus. For testing, peeps emitted when chicks were presented successively with the two tones and with periods of silence were recorded. Results of both experiments revealed a significant tendency for experimental birds to peep more to the familiar than to the novel test sound. This result demonstrates early post-hatch discrimination learning in Coturnix quail, and is in basic agreement with results from several other studies of precocial birds. It is suggested that if a similar enhancement of peeping to a familiar parent's voice occurs under natural rearing conditions, it could function adaptively to facilitate brood cohesion. Unlike previous results from several other species, simple post-hatch exposure to a sound in the absence of a familiar visual stimulus was sufficient to cause a selective enhancement of peeps to the familiar sound. The presence of a familiar visual object during training had little effect. Since discriminations developed soon after hatching and as a result of simple exposure to a sound in the apparent absence of an external reinforcer, auditory imprinting could have been involved. This interpretation was rejected, however, because peeps were selectively enhanced, not reduced as is typical in studies. An hypothesis of simple habituation of peeps also fails, for the same reason. An explanation in terms of disinhibition of peeps, resulting from habituation of some mutually exclusive alternate response, remains possible.