Curious about cuckoos

Cuckoos are as famous for their spring and summer call - listen from April to June for it echoing out across the Dales - as they are for abdicating parental responsibility, laying eggs in the nest of an unsuspecting host.

Nest rustlers

Young cuckoo chicks grow much bigger than their unsuspecting foster parents and will push any other eggs out of the nest, leaving them to be the sole focus of attention and receptor of food.

Meadow pipits and reed warblers are common victims of this remarkable egg swap strategy, and the female cuckoo has a very specialised adaptation to help her fool potential foster parents. As both of these bird species reject eggs that look different to their own, individual cuckoos specialise on one host species; reed-warbler-specialist cuckoos lay a greenish spotted egg, while meadow-pipit-specialist cuckoos lay a brownish spotted egg.

Speed is also of the essence; the cuckoo drops in, removes an egg from the nest, replaces it with her own egg and flies off all in the space of 10 seconds in order to avoid alerting the host to issues with her nest. Once hatched, the baby cuckoo’s cry sounds just like an entire clutch of hungry baby birds – appealing directly to the caretaking instincts of its foster parent and overriding any suspicion.

Cuckoo and its foster parent host bird sitting on a tree branch together the cuckoo is crying for food. — (c) Helen Fernyhough

Travel troubles

The once-familiar call of the cuckoo is disappearing from the British countryside, as cuckoos are in decline and on the red list for their UK conservation status. Loss of natural habitat and scarcer insect food in the UK have played a part, but cuckoos are now also facing increasing problems on migration to Africa.

Our cuckoos winter in the forests of the Congo after an epic journey, flying at night and crossing the Sahara in one 50-60 hour continuous flight. Curiously, they take just one of two routes to reach their destination; one southeast through Italy, where food reserves seem to be good, and one southwest through Spain.

Unfortunately increasing droughts in southwest Europe have made it difficult for these cuckoos to put on sufficient fat reserves and only half of the tracked birds survive the long desert crossing, having a serious knock-on effect on cuckoo populations in England.

Populations of cuckoos cling on in Yorkshire, including at Ashes Pasture near Ribblehead, North Cave Wetlands near Hull and Broadhead Clough near Mytholmroyd, where we are working to provide a varied habitat ideal for species like cuckoos to survive and thrive.

Did you know?

Despite 90 years of ringing, we have only recently discovered where cuckoos go over winter thanks to satellite tracking.
The cuckoo’s favourite meal is hairy caterpillars.