. Animal Life and the World of Nature; A magazine of Natural History. 320 Animal Life Purely surf ace - swimmers, like Gulls (Fig. 8), sit high, especially in the stern, and there are many gradations between these two extremes. The Grebes, however, although thorough divers, sit high ordinarily, but will sink almost level with the surface at any alarm. In diving, some birds at all events, such as Grebes and the Diving Ducks, use both feet together, as may be easily seen in the case of the latter in St. James's Park when Pochards are diving near the bridge. Under ordinary circumstances grebes an
. Animal Life and the World of Nature; A magazine of Natural History. 320 Animal Life Purely surf ace - swimmers, like Gulls (Fig. 8), sit high, especially in the stern, and there are many gradations between these two extremes. The Grebes, however, although thorough divers, sit high ordinarily, but will sink almost level with the surface at any alarm. In diving, some birds at all events, such as Grebes and the Diving Ducks, use both feet together, as may be easily seen in the case of the latter in St. James's Park when Pochards are diving near the bridge. Under ordinary circumstances grebes and diving ducks seem not to open their wings under water, but when chased the latter do so, keeping the wings half open. Guillemots fly under water in this way, not using their feet at all, and I have seen the elegant Pheasant-Tailed Jacana (Hydrophasianus chirurgus), essentially a light-floating surface-bird, do the same thing. Penguins are specially constructed for sub-aquatic flight; their wings, which only move at the shoulder-joint, being perfect paddles, and their feet not being used for propulsion under the surface (Fig. 9). They differ from other diving-birds in being able to swallow prey under water. The only aquatic Passerines, the Dippers or Water-Ouzels, also fly rmder water, using the wings half closed; then- feet are like those of ordinary Thrushes, and I am not aware that they are brought into play in swimming. It is, of course, the flight of birds which is their most interesting form of movement, and the one which is the most difficult to understand in some of its phases. Birds may fly in two ways— by beating the air with the wings, or by gliding with these motionless, although in the latter case there must be some previous impulse to give momentum. In beating, the wing is brought downwards and forwards—much more forwards than one is apt to suppose, although instan- taneous photographs have made more familiar poses which Japanese artists had apparently been a
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