Caprimulgus europaeus
Falcon or cuckoo-like, nocturnal bird with long tail and slender, pointed wings. Unmistakable when seen in areas where no other species of nightjars occur, or when singing. Hard to distinguish from Red-necked Nightjar in the field, but smaller size, smaller head compared to body and shorter tail give indications. If plumage is seen clearly, note general tone (grey brown), dark front edge of arm, broader upper wing-bar and small white throat patch.
Song unique among birds, but quite similar to Mole cricket. A mechanical, continuous slur, like the sound of a distant motorbike. As opposed to the Mole Cricket, it often "shifts gear" by changing pitch to a note approximately a fourth below the drone. Flight call a peculiar "kew-eek", with a nasal and frog-like timbre.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
