Development of species identification in ducklings: IV. Change in species-specific perception caused by auditory deprivation.

The purpose of the present experiments was to identify the change in species-specific perception that underlies the aurally deprived ducklings' lack pf preference or discrimination in the mallard versus chicken call test. Among other acoustic differences, the mallard and chicken maternal calls differ in repetition rate (3.7 and 2.3 notes/sec, respectively). The present experiments showed the dimension of repetition rate to be uppermost in the perceptual hierarchy underlying the auditory aspect of species identification in Peking ducklings. The relatively narrow species-typical repetition-rate preferences of normal Peking ducklings (about 4--6 notes/sec) is lacking in the aurally deprived ducklings, and they respond to lower rates than usual (2.3 notes/sec). This broadening of the range of responsiveness on a perceptual dimension (repetition rate) that is basic to species identification accounts for the devocal ducklings' lack of discrimination in the mallard versus chicken call test.