Several features of bird basilar papilla morphology were quantitatively studied in the starling and the pigeon in order to attempt a structure-function correlation. We confirmed and quantified several findings from earlier studies, but also obtained results contradictory to previous reports. The greatest discrepancies concerned the pattern of hair cell orientation. By including the results from other investigations, we describe a 'typical' avian basilar papilla and on this basis the specializations within individual species. These morphological specializations are discussed in the context of the available physiological data.