Perception of conspecific faces by budgerigars (Melopsittacus undulatus): II. Synthetic models

Perception of faces by budgerigars (Melopsittacus undulatus) was studied with computerized images modeled after natural faces. Individual facial characteristics were varied with all others held constant; then relative importance among several features was determined by varying each within a single experiment. Characteristics with the potential to signal important biological information (e.g., age or sex) were perceptually salient, whereas characteristics that vary among faces but have limited potential to signal important information were not. Model faces were also presented in a normal or an altered configuration. Birds discriminated among faces in a normal configuration more easily than among models with an altered configuration even when the facial features on which the discrimination was based differed in the same way; this suggests that configurational cues play an important role in face perception by budgerigars.