Sour foods are often avoided by mammals, but many birds regularly feed on highly acidic fruits. Evolution has provided them with a clever strategy to eat extremely acidic fruit. A new study that birds‘ sour receptors shut down when exposed to acidic food, reducing the transmission of sour signals and thus influencing their perception and tolerance. The findings suggest that the molecular evolution of sour receptors in birds may have played a key role in their evolution and diversification. Interestingly, in songbirds, this appears to have occurred at the same time as the evolution of sweet taste perception, suggesting a possible coevolution of sour and sweet taste.