The Nightjar or Goatsucker (Caprimulgus europaeus), Fig. 23, upper figure, included in the Fissirostral (Split-bill) section of the Insessores, family Caprimulgidae and sub-family Caprimulginae, gains its appellation from the shrill whirring sound which it produces. The name of Goatsucker is derived from the superstitious notion that it sucks goats. It arrives in Britain at the beginning of May and leaves in September or later. It may be seen, on the approach of evening, silently wheeling round the trees, capturing the nocturnal moths and beetles and gnats. When flying the mouth is continually open, and the interior is covered with a glutinous substance, and this with the bristles placed along each side of the upper mandible prevents any insect secured from escaping without shutting it. The flying with the mouth open occasions the whirring noise made while chasing prey, and is low or loud according to the velocity with which the bird moves. When perched, usually lengthwise on a bare twig, it utters a jarring note. It is solitary in its habits and generally seen alone.

The colours of the plumage are black, white, brown, grey, and ferruginous, disposed in the forms of bars, spots and streaks, which have a beautiful effect, the male having an oval white spot near the end of the three first quill feathers. Its length is about 10 in. The Goatsuckers frequent moors and wild heathy tracts, especially where ferns abound. They make no nest, but the female deposits two or three eggs on the bare ground, which are of a dull white spotted with brown.