DIVING BIRDS AT THE ZOO 
81 
only fed once a day, and the appearance of the keeper 
with his pail of live gudgeon is the signal for sudden 
and intense excitement in the cages. The penguins 
wave their little flippers and waddle to the door, 
whence they peer eagerly down the wooden steps 
leading to the pool ; the cormorant croaks and sways 
from side to side, and the darters poise their snaky 
heads and spread their bat-like wings. At the waters 
edge the penguins do not launch themselves upon the 
surface like other water-fowl, but instantly plunge 
beneath. Once below water an astonishing change 
takes place. The slow, ungainly bird is transformed 
into a swift and brilliant creature, beaded with globules 
of quicksilver where the air clings to the close 
feathers, and flying through the clear and waveless 
depths with arrowy speed, and powers of turning far 
greater than in any known form of aerial flight. The 
rapid and steady strokes of the wings are exactly 
similar to those of the air birds, whilst its feet float 
straight out level with the body, unused for pro- 
pulsion, or even as rudders, and as little needed in its 
progress as those of a wild duck on the wing. The 
twists and turns necessary to follow the active little 
fish are made wholly by the strokes of one wing and 
the cessation of movement in the other ; and the fish 
are chased, caught, and swallowed without the slightest 
relaxation of speed, in a submarine flight which is 
quite as rapid as that of most birds which take their 
prey in mid-air. In less than two minutes some 
thirty gudgeon are caught and swallowed below water, 
