EVEN songbirds have their favourite offspring. Black redstarts can identify their chicks from differences in their pleas for food, enabling the parents to split the work of feeding the entire brood.
Tudor Draganoiu of the University of Leiden in the Netherlands and his colleagues spent three summers studying the interactions between black redstart (Phoenicurus ochruros) parents and chicks. They recorded the begging call of each fledgling and then played them back from carefully hidden speakers.
By observing the amount of parental interest in different begging calls, Draganoiu and his colleagues were able to show that parents divided up their broods,…
