This paper challenges the assumption that improvisation is a process unique to humans. Despite the general reluctance of biologists to consider birdsong "music," they routinely comment on improvisation found in the signals of songbirds. The Australian pied butcherbird (Cracticus nigrogularis) is such a species. Analysis (including transcriptions and sonograms) of solo song, duets and mimicry illustrates their remarkable preoccupation with novelty and variety, and traces improvisation's role in the creation of their complex song culture. The author suggests further zoömusicological case studies for the relevance this research could have to other human (musical) capacities.