Bird songs are learned when young and are used for territorial defense and courtship behavior during the breeding season. Vocal learning early in life requires auditory feedback in which young birds hear their own vocalizations. This auditory feedback is necessary even in adulthood, as birds hear their own songs to maintain stability and regularity. In many species (such as songbirds), vocal learning is limited to juvenile stage, but budgerigars continue to learn throughout adulthood. Recent studies have suggested that songbirds may also have the ability to modify their learned song in adulthood. We address the question of song plasticity in adult birds by comparing budgerigars and songbirds.