When I was working in Sydney I spent a lot of my spare time watching birds, and taking photographs for record purposes. I enjoyed watching the fairy wrens - especially when the male got very angry with the impostor he could see in the car wing mirror.
I now find the birds had a verbal trick to enable them to discover when they have a cuckoo chick in the nest. The incubating female sings an individual trill to the eggs - different for each female. The in-egg chicks learn the call and when the eggs hatch they use a segment from the mother's individual song as part of their begging call. If a chick does not use its mother's "name" it must be a cuckoo imposter - and the nest is abandoned. [More Information]
Interestingly most of the publicity I have seen uses the brightly coloured male to illustrate the species - when the female, whose song was the subject of the research is just a harder to see LBJ (Little Brown Job)