Dooling, R.J., Gephart, B.F., Price, P.H., McHale, C., and Brauth, S.E. (1987). Effects of deafening on the contact call of the budgerigar (Melopsittacus undulatus). Animal Behavior, 35, 1264-1266.

Vocal development is rigid and inflexible in some species of birds (i.e. the domestic chicken, Gallus domesticus, ring dove, Strepropelia risoria, and turkey, Meleagris gallopavo) while in others, notably songbirds, vocal development is guided by learning and is often critically dependent on the influence of the auditory environment (Konishi 1978, 1985). Many psittacines, including the budgerigar, Melopsittacus undulatus, are known for their ability to mimic a variety of sounds including human speech, Yet, so far as we know, the classic experiments of deafening, isolation-rearing and song tutoring aimed at delineating the roles of auditory feedback and external acoustic models have not been conducted with psittacines. One tutoring experiment has shown that budgerigars can imitate tonal patterns and song segments from other avian species (Gramza 1970), so it would not be too surprising if this mimetic capacity is also involved in the development of species-specific vocalizations. As a first step in comparing vocal development in budgerigars with that of songbirds, we sought to determine whether hearing is required for the development of normal vocalizations.