The female cuckoo mimics the call of a hawk to distract nest-owners. Credit: blickwinkel/Alamy

The BBC has just screened an adaptation of Harry Potter author J. K. Rowling’s detective story The Cuckoo’s Calling, and many viewers have been left confused. No spoilers here: but for many watching, the twist ending was a little hard to follow, the misdirection a little too effective. But then the book itself was famously published with some considerable misdirection: Rowling wrote it under the pen name Robert Galbraith because she wanted to see how the public would respond to her passing off her own work as someone else’s.

The reverse is more usually true: rather than conceal genuine achievements, fakers employ deception to take undeserved credit for work they themselves didn’t carry out. That’s a sensible strategy in the animal kingdom, too. More reward for less effort is a recipe for success in the ongoing natural struggle for resources and survival. Parasites get a bad press, but they keep getting away with it. All of which brings us neatly from The Cuckoo’s Calling to a cuckoo calling.

The common cuckoo (Cuculus canorus) is a parasite with good PR. Despite deceiving other birds into hatching its eggs and raising its young — often at the expense of the cuckolded dupe’s legitimate offspring — the cuckoo seems to have emerged with its reputation not only intact but enhanced. William Shakespeare may have labelled the cuckoo call a “word of fear unpleasing to a married ear”, but people far and wide still willingly invite the sound into their homes to mark the hourly passing of time.

The female of the species is sneakier than the male. Whereas the proud and visible male cuckoo is responsible for that famous two-note call, it’s the female that does the actual dirty work of leaving usurpers in the homes of others. And her call is very different and rarely heard. But, as it turns out, it too is part of the parasitical package.

In a paper published this week (J. E. York and N. B. Davies Nature Ecol. Evol.; 2017), scientists at the University of Cambridge, UK, reveal a dark twist behind the (female) cuckoo’s calling. The researchers studied the behaviour and impact of the sounds of the birds in a series of field experiments at nearby Wicken Fen. After the female has visited a target nest, she deliberately mimics the frightening calls of a hawk, which puts the parent birds on high alert and distracts them from spotting, say, a new, unusually large and differently coloured egg in their happy home. Instead of discovering the cuckoo’s deception, the parent birds — in this case, reed warblers — then spent their time stretching their necks to peer over the rim of the nest, scanning the sky for incoming hungry hawks. 

It’s another example, the researchers say, of how parasites can manipulate and redirect the behaviour of their host species to their own advantage. And this particular cuckoo’s calling sounds — spoiler alert — like a little chuckle.