European nightjar
The European nightjar, common goatsucker, Eurasian nightjar or just nightjar is a crepuscular and nocturnal bird in the nightjar family that breeds across most of Europe and the Palearctic to Mongolia and Northwestern China. The Latin generic name refers to the old myth that the nocturnal nightjar suckled from goats, causing them to cease to give milk. The six subspecies differ clinally, the birds becoming smaller and paler towards the east of the range. All populations are migratory, wintering in sub-Saharan Africa. Their densely patterned grey and brown plumage makes individuals difficult to see in the daytime when they rest on the ground or perch motionless along a branch, although the male shows white patches in the wings and tail as he flies at night.
The preferred habitat is dry, open country with some trees and small bushes, such as heaths, forest clearings or newly planted woodland. The male European nightjar occupies a territory in spring and advertises his presence with a distinctive sustained churring trill from a perch. He patrols his territory with wings held in a V and tail fanned, chasing intruders while wing-clapping and calling. Wing clapping also occurs when the male chases the female in a spiralling display flight. The European nightjar does not build a nest, and its two grey and brown blotched eggs are laid directly on the ground; they hatch after about 17–21 days and the downy chicks fledge in another 16–17 days.
The European nightjar feeds on a wide variety of flying insects, which it seizes in flight, often fly-catching from a perch. It hunts by sight, silhouetting its prey against the night sky. Its eyes are relatively large, each with a reflective layer, which improves night vision. It appears not to rely on its hearing to find insects and does not echolocate. Drinking and bathing take place during flight. Although it suffers a degree of predation and parasitism, the main threats to the species are habitat loss, disturbance and a reduction of its insect prey through pesticide use. Despite population decreases, its large numbers and huge breeding range mean that it is classified by the International Union for Conservation of Nature as being of least concern.
Taxonomy
The European nightjar was described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae under its current scientific name. Caprimulgus is derived from the Latin capra, "nanny goat", and mulgere, "to milk", referring to an old myth that nightjars suck milk from goats, and the species name, europaeus is Latin for "European". The common name "nightjar", first recorded in 1630, refers to the nocturnal habits of the bird, the second part of the name deriving from the distinctive churring song. Old or local names refer to the song, "churn owl", habitat, "fern owl", or diet, "dor hawk" and "moth hawk".The nightjars, Caprimulgidae, is a large family of mostly nocturnal insect-eating birds. The largest and most widespread genus is Caprimulgus, characterised by stiff bristles around the mouth, long pointed wings, a comb-like middle claw and patterned plumage. Adult males, and sometimes females, have white markings in the wing and tail, shown to serve as male quality indicators. Within the genus, the European nightjar forms a superspecies with the rufous-cheeked nightjar and the sombre nightjar, African species with similar songs. It is replaced further east in Asia by the jungle nightjar which occupies similar habitat.
Subspecies
There are six recognised subspecies, although the differences are mainly clinal; birds become smaller and paler in the east of the range and the males have larger white wing spots. Birds of intermediate appearance occur where the subspecies' ranges overlap.The fossil record is deficient, but it is likely that these poorly defined subspecies diverged as global temperature rose over the last 10,000 years or so. Only one record of the species possibly dates back to the late Eocene.
Description
The European nightjar is long, with a wingspan. The male weighs and the female. The adult of the nominate subspecies has greyish-brown upperparts with dark streaking, a pale buff hindneck collar and a white moustachial line. The closed wing is grey with buff spotting, and the underparts are greyish-brown, with brown barring and buff spots. The bill is blackish, the iris is dark brown and the legs and feet are brown.The flight on long pointed wings is noiseless, due to their soft plumage, and very buoyant. Flying birds can be sexed since the male has a white wing patch across three primary feathers and white tips to the two outer tail feathers, whereas females do not show any white in flight. Chicks have downy brown and buff plumage, and the fledged young are similar in appearance to the adult female. Adults moult their body feathers from June onwards after breeding, suspend the process while migrating, and replace the tail and flight feathers on the wintering grounds. Moult is completed between January and March. Immature birds follow a similar moult strategy to the adults unless they are from late broods, in which case the entire moult may take place in Africa.
Other nightjar species occur in parts of the breeding and wintering ranges. The red-necked nightjar breeds in the Iberian Peninsula and northwest Africa; it is larger, greyer and longer winged than the European nightjar, and has a broad buff collar and more conspicuous white markings on the wings and tail. Wintering European nightjars in Africa may overlap with the related rufous-cheeked and sombre nightjars. Both have a more prominent buff hind-neck collar and more spotting on the wing coverts. The sombre nightjar is also much darker than its European cousin. Given their nocturnal habits, cryptic plumage and difficulty of observation, nightjar observation "is as much a matter of fortune as effort or knowledge".
Voice
The male European nightjar's song is a sustained churring trill, given continuously for up to 10 minutes with occasional shifts of speed or pitch. It is delivered from a perch, and the male may move around its territory using different song posts. Singing is more frequent at dawn and dusk than during the night, and is reduced in poor weather. The song may end with a bubbling trill and wing-clapping, perhaps indicating the approach of a female. Migrating or wintering birds sometimes sing. Individual male nightjars can be identified by analysing the rate and length of the pulses in their songs. Even a singing male may be hard to locate; the perched bird is difficult to spot in low light conditions, and the song has a ventriloquial quality as the singer turns his head. The song is easily audible at, and can be heard at in good conditions; it can be confused with the very similar sound of the European mole cricket.The female does not sing, but when on the wing, both sexes give a short ' call, also used when chasing predators. Other calls include variations on a sharp chuck when alarmed, hisses given by adults when handled or chicks when disturbed, and an assortment of ', muffled oak, oak and murmurs given at the nest. Large young have a threat display with the mouth opened wide while hissing loudly.
Despite the name, wing-clapping does not involve contact between the two wing tips over the bird's back as was once thought. The sound is produced in a whiplash-like way as each wing cracks down.
Distribution and habitat
The breeding range of the European nightjar comprises Europe north to around latitude 64°N and Asia north to about 60°N and east to Lake Baikal and eastern Mongolia. The southern limits are northwestern Africa, Iraq, Iran and the northwestern Himalayas. This nightjar formerly bred in Syria and Lebanon.All populations are migratory, and most birds winter in Africa south of the Sahara, with just a few records from Pakistan, Morocco and Israel. Migration is mainly at night, singly or in loose groups of up to twenty birds. European breeders cross the Mediterranean and North Africa, whereas eastern populations move through the Middle East and East Africa. Some Asian birds may therefore cross 100° of longitude on their travels. Most birds start their migration at the time of a full moon.
Most birds winter in eastern or southeastern Africa, although individuals of the nominate race have been recently discovered wintering in the Democratic Republic of the Congo; records elsewhere in West Africa may be wintering birds of this subspecies or C. e. meridionalis. Most autumn migration takes place from August to September, and the birds return to the breeding grounds by May. Recent tracking data has revealed that European nightjars have a loop migration from Western Europe to sub-equatorial Africa where they have to cross several ecological barriers. Individuals use similar stop-over sites as do other European migrants. Vagrants have occurred in Iceland, the Faroe Islands, the Seychelles, the Azores, Madeira and the Canary Islands.
The European nightjar is a bird of dry, open country with some trees and small bushes, such as heaths, commons, moorland, forest clearings or felled or newly planted woodland. When breeding, it avoids treeless or heavily wooded areas, cities, mountains, and farmland, but it often feeds over wetlands, cultivation or gardens. In winter it uses a wider range of open habitats including acacia steppe, sandy country and highlands. It has been recorded at altitudes of on the breeding grounds and in the wintering areas.
Behaviour
The European nightjar is crepuscular and nocturnal. During the day it rests on the ground, often in a partly shaded location, or perches motionless lengthwise along an open branch or a similar low perch. The cryptic plumage makes it difficult to see in the daytime, and birds on the ground, if they are not already in shade, will turn occasionally to face the sun thereby minimising their shadow. If it feels threatened, the nightjar flattens itself to the ground with eyes almost closed, flying only when the intruder is away. It may call or wing clap as it goes, and land as far as from where it was flushed. In the wintering area it often roosts on the ground but also uses tree branches up to high. Roost sites at both the breeding and wintering grounds are used regularly if they are undisturbed, sometimes for weeks at a time.Like other nightjars, it will sit on roads or paths during the night and hover to investigate large intruders such as deer or humans. It may be mobbed by birds while there is still light, and by bats, other nightjar species or Eurasian woodcocks during the night. Owls and other predators such as red foxes will be mobbed by both male and female European nightjars. Like other aerial birds, such as swifts and swallows, nightjars make a quick plunge into water to wash. They have a unique serrated comb-like structure on the middle claw, which is used to preen and perhaps to remove parasites.
In cold or inclement weather, several nightjar species can slow their metabolism and go into torpor, notably the common poorwill, which will maintain that state for weeks. The European nightjar has been observed in captivity to be able to maintain a state of torpor for at least eight days without harm, but the relevance of this to wild birds is unknown.