Lesley Gorman, RSPB Visitor Experience Manager at RSPB Arne, tells us about the elusive Cuckoo that can be heard at the reserve, although it's iconic sound is sadly declining across England.
When Wordsworth wrote: “While I am lying on the grass, Thy twofold shout I hear; From hill to hill it seems to pass, At once far off, and near,” he was describing one of our best-known bird calls, that of the Cuckoo. If you are lucky this month you might hear the famous ‘cuck-coo’ sound at RSPB Arne nature reserve. This long-distance traveller arrived in the UK from mid-April, after completing an incredible 9000-mile round trip to central Africa (where it over winters) and back. At RSPB Arne we have heathlands, woodlands, wild scrub and grassy places where wildlife can thrive - so it’s a great place to come and hear a Cuckoo.
Photo above: Adult male Cuckoo perched in a tree by Ben Andrew (rspb-images.com)
The call of the male Cuckoo is said to herald the start of spring and the sound can travel quite some distance. Although most people know what a Cuckoo sounds like, how many have heard one? (listen here) Sadly, not as many in recent years as the populations of this iconic bird have declined so much in England that it is now a Red Listed bird of conservation concern (Cuckoo numbers have increased in Scotland over the last 25 years). Cuckoos mainly eat hairy caterpillars of moths and butterflies – prey that many other birds avoid. Research by RSPB and partners has shown that Cuckoo food has declined most in the same (farmland-dominated) areas where Cuckoos have also declined most. However, Cuckoos tend to persist in areas with wild scrub and grassland – the habitats still providing the most food.
Photo above: Adult male Cuckoo with grub in it's mouth by RSPB (rspb-images.com)
Cuckoos are secretive birds and hide in the leafy cover of open woodland, upland heathland or reedbeds. They tend to avoid built up areas. If you do spot one you will see a bird that looks strangely like a cross between a Dove and a Sparrowhawk. I read a great description that said this sleek bird looks like it got dressed in the dark with its mismatched grey head and chest and its white and brown stripy underparts.
Smaller birds can be spooked by the Cuckoo’s likeness to a small bird of prey in flight. They leave their nests in panic allowing the wily female Cuckoo to locate her target. She then swoops in and quickly deposits her single egg in the nest, ejecting one of the original eggs in its place. Cuckoos lay in nests that belong to the same species as those that reared them and, in the UK, Reed Warblers, Meadow Pipits or Dunnocks are the most common hosts.
Photo above: Meadow Pipit perched on bracken, by Tom Marshall (rspb-images.com)
If a female Cuckoo is raised by, for example, Meadow Pipits, she will likely continue parasitising Meadow Pipits when she reaches breeding age. She is genetically predisposed to pick the same host species. And incredibly, overtime Cuckoos adapt the colour of their eggs to match those that the host species lays, so that they better blend in and essentially trick the host parent into thinking the Cuckoo egg is their own. Isn't nature fantastic?!
Cuckoo eggs hatch 12 days after laying and the newly hatched chick proceeds to evict any remaining eggs or chicks. Before it's eyes are even open it moves around the nest, balances the original eggs on its back and pushes them out of the nest, as well as any chicks that hatched before it, claiming the entire nest and feeding parents for itself. 19 days later, the Cuckoo chick leaves the nest but continues to demand food for a further two weeks. The chosen foster parents look tiny in comparison to the large chick, and they have to work hard to satisfy its hungry demands. To ensure the Cuckoo chick gets enough food it mimics the sound of a whole nest full of chicks, again tricking the host parents to bring back enough food.
Photo above: Newly hatched Cuckoo chick ejecting Reed Warbler eggs from out of the nest by Mike Richards (rspb-images.com)
Leaving their young being well looked after by the host bird, the adult Cuckoos can make an early departure on their long journey back to Africa, the young birds following on later.
Discover more about RSPB Arne and the wonderful wildlife that calls it home by enjoying one of our many monthly nature events at the reserve, here.