Development of species identification in ducklings: II. Experimental prevention of perceptual deficit caused by...

Devocalized-isolated ducklings are relatively insensitive to the higher frequencies in their species' maternal call 24 hr after hatching. To assess the efficacy of various sounds in preventing this high-frequency perceptual deficit, devocalized-isolated embryos were exposed to one of three calls and tested with normal versus high-frequency attenuated maternal calls 24 hr after hatching. The embryonic vocalization (contact-contentment call) that most closely matched the region of the devocalized ducklings' greatest insensitivity (1,500-2,500 Hz) proved most efficacious in remedying (preventing) the high-frequency perceptual deficit. Exposure to the embryonic alarm-distress call was somewhat effective, whereas exposure to low-frequency white noise was not effective at all. This finding suggests that the normal development of innate behavior is partially dependent upon prior experience as well as upon intrinsic processes of neural maturation. Although normally occurring embryonic auditory experience does not induce the preference for the maternal call in this species, such experience does contribute to the sharpness of the discriminative basis of the preference 24 hr after hatching.