Scientists at Johns Hopkins in the US have found that how well a male Starling sings is a strong indication of the health of his immune system and hence his suitability as a mate. Dr. Duffy and Dr. Ball looked at the singing abilities of 16 adult male European Starlings in an outdoor aviary. They compared the strengths' of their immune systems with how many songs they sang, and how long each song was. They found that they best singers also had the best immune systems. Presumably female Starlings pay a lot of attention to singing because it indicates a healthy mate who is likely to father healthy chicks. How the link between immunity and song quality comes about though, we don't know, but as the researchers point out, it might provide important clues to how the immune system is controlled at large which has implications for many diseases in animals and people.