Passwords are private pieces of information that protect important aspects of our lives. They lose their main function when known by others, and they need to be complex enough not to be guessed too easily. A fascinating study published in Current Biology suggests that a species of birds has developed a system of communication between parents and offspring that resembles passwords. Families of Superb Fairywren use this system to recognize each other as a defense against an intruding parasite species.
The Superb Fairywren is a passerine bird that has faced quite a challenge during its evolutionary history. Another species, the Horsfield’s Bronze Cuckoo, is using their nests and benefiting from their parental care. Indeed, Horsfield’s Bronze Cuckoo are parasite species; they lay eggs that look like Superb Fairywren eggs in the Fairywren’s nests. If the Fairywrens were to care for these young, this would have important consequences. They would spend a considerable amount of energy caring for youngs that are not theirs; even worse, after hatching, the Cuckoos evict the Fairywren’s actual eggs to monopolize parental care.
The communication system that Fairywrens have developed to protect themselves against this threat is quite impressive and it is the subject of the article published by Colombelli-Négrel and colleagues1. They show that mother Fairywrens have an incubation call – a call that they use while caring for the eggs. Nestlings can learn key elements of the call while in the egg and they can later use that call to be recognized by their mother. The call is learned before the Bronze Cuckoo lay their own eggs in the nest, which guards the families against the unwanted intruder. The call is also communicated to the male mate who can also use it to recognize the nestlings.
The study identifies a fascinating behavioral example of social recognition in animals. Further research might reveal the brain mechanisms involved, but for now we know very little about how such behaviors are handled by the brain. We also do not know if these mechanisms share similarities with those at play when other species, like us, recognize the people we know.
1. Colombelli-Négrel D, Hauber ME, Robertson J, Sulloway FJ, Hoi H, Griggio M, Kleindorfer S. (2012) Embryonic Learning of Vocal Passwords in Superb Fairy-Wrens Reveals Intruder Cuckoo Nestlings Current Biology.