THE MOVEMENTS. 
27 
of the latter. The art of rowing is most thoroughly 
understood by swimming-birds. First, the foot, the 
toes of which are spread out at the side, is drawn toge¬ 
ther, so that the middle toe presents itself in advance 
of the remaining two or three; at the same time the 
leg is moved upwards and forwards. With the backward 
pressure the foot again partially expands, or, when 
webbed, as fully as this will permit of. While the bird is 
swimming quietly and steadily the motion of the feet is 
alternate; when, however, going very fast, their action is 
simultaneous, which then gives with each stroke of the 
feet a corresponding forward motion. Should a bird rise 
up on end, as Ducks often do, to shake the water from 
their wings, or, in the same position, to attract the 
attention of its companions by calling out, then a move¬ 
ment of the tail is brought into play, so as to preserve the 
equilibrium of the body. To effect this the legs are moved 
from the front to the back, and the tail from back to front, 
one against the other; by this means the water lying 
between the feet and tail is pressed downwards, and the 
bird is raised by the shock of the resistance. With 
respect to the rapidity with which a bird can swim on the 
surface of the water, we have seen a great crested Grebe 
(Podiceps cristatus) keep pace with a steamer. To dive 
beneath the surface every swimming-bird has to give 
with its full force a stroke simultaneously with both feet. 
With many true divers this stroke is so powerful as to 
throw the bird forward over the surface of the water 
before it disappears head-first in the flood; with others 
this spring, clear of the water, does not take place. Pre¬ 
viously to diving the plumage is first laid as close to 
the body as possible, so as to lessen its circumference; 
when again rising to the surface the feathers are, on the 
