74 THE BIRDS OF HELIGOLAND 



perpendicular position, head downwards, and driving its body down 

 into the water by powerful upward strokes of its broad swimming 

 feet. The two actions have as little in common as has the ordinary 

 flight of birds by means of the mechanical motion of their wings 

 with their soaring flight on motionless expanded pinions. 



These Divers, moreover, and other related aquatic birds, avail 

 themselves of this capacity of immersing their body and of keep- 

 ing it below the surface for any desirable time, not only for the 

 purpose of escaping from danger, but also, as I had an opportunity 

 of observing, with the object of surprising and securing some 

 coveted prey. Many years ago I was a witness of a highly interest- 

 ing case of this nature in the Zoological Gardens at Hamburg. On 

 a moderately sized pond a Cormorant had immersed its body com- 

 pletely in the water, its neck being quite drawn in, so that only its 

 head was visible above the surface ; in this position the bird lay 

 without stirring. I could not conceive what was the meaning of 

 this extraordinary behaviour on the part of the bird, and watched 

 it at some distance. A considerable number of Swallows were, after 

 their manner, skimming along the surface of the water, and as one 

 of them, boding no ill, sped close past the Cormorant, the latter 

 shooting out its neck to its full length, swift as lightning made a 

 snap at the bird. After two other unsuccessful attempts, the wily 

 robber at length succeeded in snatching a victim, which he swal- 

 lowed, after giving it two or three shakes in the water. He then 

 again immersed his body as before, and lay motionless in ambush 

 for further prey. I ought to add that the pond in the middle, 

 where the Cormorant lay concealed, was about four feet deep, and 

 entirely free from any plant growth, so that the bird could not 

 possibly have obtained any hold by its feet below. 



That the body of a bird, light as a cork as compared with 

 the water, should be able to remain for a protracted period 

 beneath the surface, is indeed as great a physical problem as the 

 motionless soaring flight of some other species of birds in a calm 

 and almost weightless atmosphere. Serious doubts have been ex- 

 pressed as to the accuracy of my observations in regard to the latter 

 of these phenomena ; but every sportsman and naturalist who has 

 ever engaged in a hunt after Divers will endorse the accuracy of 

 the facts I have related in regard to them. 



The Great Northern Diver breeds throughout the whole of 

 Arctic America, from Alaska to Greenland, and also very numerously 

 in Iceland. 



