British Wildlife of the Week
If you take a walk on a heath on a warm, still summer evening in southern England, you may hear a very strange sound from above you – a so-called ‘churr’. It has an otherworldly, almost mechanical quality. Centuries ago, people thought this was the sound of witches cackling in the bushes. But it is, in fact, the song of a bird – a male nightjar, to be precise.
The European nightjar is a mysterious, wide-mouthed, night-flying bird that visits Britain, mainland Europe and parts of Asia during the summer months. During the day, it sits motionless on the ground or roosts lengthways along a branch; its cryptic, greyish-brown plumage with white speckles – the colour of dead bracken or bark – makes the bird virtually impossible to see.
In the late evening, however, the nightjar stirs and takes to the air to hunt flying insects. With its long, slender wings and long tail, it is an exceptionally agile flier, twisting and turning above pastures and woodlands. The flight is light, buoyant and almost dancing, more like a giant bat than a bird. Though the nightjar’s bill is very short, it has a capacious gape, which is perfect for collecting moths and flies. There is also a series of stiff bristles around the edge of the mouth, which may help locate insects or funnel them into its beak.
Once darkness has fully fallen, the nightjar is largely undetectable, so there is normally only a brief window of opportunity to see this bird, at dawn and dusk, when territorial males make themselves more conspicuous than usual. The male nightjar’s strange, surreal churring song – a mechanical yet musical rattle – is most often heard between late May and late July. The churring is sometimes punctuated by a series of short wing claps, which the males use to defend their territory, intimidate rivals, and court a potential mate. This bird aligns its breeding season to the lunar cycle, matching the period of its chicks’ peak food demand with a full moon, which, in cloudless conditions, provides enough light for nightjar parents to forage deep into the night.
The nightjar’s unusual appearance, large dark eyes, crepuscular habits, and eerie, jarring song have made it the subject of much superstition through the ages. There is an old legend, for example, stating that unbaptised children were turned into nightjars when they died. Another longstanding myth, old even in the time of the Greek philosopher Aristotle, was that they sucked the teats of domestic goats at night until the livestock had gone blind and been drained of milk, hence the now-obsolete folk name ‘goatsucker’.
It’s not too hard to see how this seemingly nonsensical conclusion was reached. Nightjars are often attracted to grazing pastures and paddocks containing domestic animals because of the high concentration of insects – particularly biting ones – found there at dusk. It would only have taken a relatively small leap of imagination to go from seeing these enigmatic birds flying around livestock in low light conditions to thinking they were perhaps having a drink of milk from the goats as they did so. This belief was so widespread that, even today, the nightjar’s scientific name reflects it: Caprimulgus is derived from the Latin words capra, ‘nanny goat’, and mulgere, ‘to milk’.
In the next British Wildlife of the Week, we’ll be looking at an exotic-looking, alien bird, the ring-necked parakeet, in honour of World Parrot Day.