"This cuckoo is not alone in its freeloading. About 1 per cent of bird species act this way – they’re ‘obligate brood parasites’. Laying your egg in another bird’s nest lets you access the world’s ultimate crèche: there’s 24/7 care, no waiting list, and you never have to pay the bill. It’s the bird equivalent of throwing a baby out of a high chair, plonking your own infant in its place, then heading to the pub. For ever. A female common cuckoo chucks one egg out of her chosen host’s nest before laying her own egg in its place. If the cuckoo egg hatches first, the early-bird chick pushes its rival eggs out of the nest. Now it can catch the worm – it’s won the undivided attention of its new foster-parents. And if the cuckoo emerges after the host bird’s chicks, it shoves its step-brothers and sisters over the edge to their death. It’s the story of Cinderella, only an Ugly Sister wins and there’s no Fairy Godmother."