Goat-sucker, or Fern-owl, in ornithology, a genus of birds belonging to the order of passerines. The beak is incurvated, small, tapering, and depressed at the base; the mouth opens very wide.

1. The Eurotopus, with the tubes of the nostrils hardly visible. It feeds on moths, gnats, dorrors, or chaffers; from which Charleton calls it a dorr-bawk, its food being entirely of that species of beetle during the month of July, the period of that insect's flight in this country. This bird migrates. It makes but a short stay with us: appears the latter end of May; and disappears, in the northern parts of our island, the latter end of August; but, in the southern, stays above a month later. It inhabits all parts of Britain from Cornwall to the county of Roos. Mr Scopoli seems to credit the report of their sucking the teats of goats, an error delivered down from the days of Aristotle. Its notes are most singular. The loudest so much resembles that of a large spinning wheel, that the Welsh call this bird aderyn y dreolli, or the wheel-bird. It begins its song most punctually on the close of day, sitting usually on a bare bough, with the head lower than the tail, the lower jaw quivering with the efforts. The noise is so very violent, as to give a sensible vibration to any little building it chances to alight on and emit this species of note. The other is a sharp squeak, which it repeats often; this seems a note of love, as it is observed to reiterate it when in pursuit of the female among the trees. It lays its eggs on the bare ground; usually two: they are of a long form, of a whitish hue, prettily marbled with reddish brown. The length of this bird is 10½ inches; extent 22. Plumage, a beautiful mixture of white, black, ash-colour, and ferruginous, disposed in lines, bars, and spots. The male is distinguished from the female by a great oval white spot near the end of the three first quill-feathers, and another on the outmost feathers of the tail. This is the only one of the genus which is found in Europe. A variety less in size, being only eight inches in length, inhabits Virginia, in summer; arrives there towards the middle of April, and frequents the mountainous parts, but will frequently approach the houses in the evening, where it settles on a rail or post, and cries for several times together very loud, somewhat like the word whip-poor-whip, or whip-poor-will, the first and last syllables pronounced the loudest. After continuing in one place for some time, it flies to another, and does the same; sometimes four or five cry all together: this noise it begins just after sun-set, and continues at intervals till just before sunrise. It does not catch insects always on the wing; for it frequently sits upon a convenient place, and leaps up after them as they fly by, and returns to the same spot again. It makes no nest, but lays the eggs, which are two in number, and of a dull green with dusky spots and streaks, on the bare ground in the open fields. Kalm says that the flesh is good to eat. Another variety, larger, inhabits Virginia and Carolina; where it is called the rain-bird, because it never appears in the day-time, except when the sky, being obscured with clouds, betokens rain. It is said to lay the eggs on the ground, and that they are not unlike those of the Lapwing.

2. The Americanus, has the tubes of the nostrils very conspicuous. It is a night bird, and is found in America.

There are several other species or varieties inhabiting different countries, and differently marked, but all nearly similar in their manners.