Functional maps of auditory response areas were established from multiunit recordings in the caudal telencephalon of male zebra finches. The response criterion was a difference of activity from the spontaneous discharge level. Pure tones and conspecific song were used as stimuli. The auditory part of the caudal telencephalon in zebra finches can be subdivided into six functionally separated centres. The definition of separate areas is based on the existence of tonotopic gradients in each single area and on differences in neural response behaviour between areas. The anatomical area L2a is functionally subdivided into two tonotopic centres. Other areas can be identified by anatomy and function. The borders vary slightly depending on the description method.