The members of this Family are true denizens of the ocean, {73}often met with many hundred miles from land; they will then hover constantly about a vessel, or even alight fearlessly on the rigging. They traverse the air with rapid sweeping flight, accompanied by constant quick pulsations of the wings; at one time soaring aloft to wheel in circles, at another plunging into the water from an immense height, though appearing again in a moment to float upon the surface. Their gait on land is shuffling, while they can hardly rise from level ground; the note is a harsh croak or chatter; the food consists of fish, squids, and other produce of the sea. No nest is made, but a single reddish-brown or buff egg, with spots and frecklings of red-brown, purplish or grey, is deposited in a hole or crevice in a cliff, among rocks, or even in a cavity in a rotten tree, both sexes assisting in incubation.[77] The parents sit very closely, screaming, pecking, and snapping when disturbed; in some places they are habitually caught while breeding, and deprived of the long tail-feathers, which are used for decorations. [Illustration: FIG. 20.–Tropic Bird. _Phaëthon aethereus._ × ⅛.] Fam. II. SULIDAE.–_Sula bassana_, the Gannet or Solan Goose, which nests at several stations off the west of Great Britain, in Ireland, and on the well-known Bass Rock, extends thence to Iceland, and down the American coast to Nova Scotia, while it strays to Greenland, and in winter reaches the Gulf of Mexico and northern Africa. The plumage is white, with a buff tinge on the head and neck, and black primaries; the bill is whitish, the feet dusky, and the naked skin round the eye and down the centre of the throat blackish-blue. _S. capensis_ of South Africa and _S. serrator_ of Australia are similar to the above, but the former has the rectrices black, the latter the four median feathers blackish-brown. {74}[Illustration: FIG. 21.–Gannet. _Sula bassana._ × ⅐.]