GREAT NORTHERN-DIVER 445 



it was unable to get out, and the lightkeeper was able to watch it for 

 over an hour. When travelling at its greatest speed, but with the aid 

 of the feet alone, the eye could detect hardly anything but a streak 

 from one end of the pool to the other. 1 Both feet were invariably 

 used simultaneously. Possibly this was due to the alarm felt by the 

 bird in its unusual position, for Mr. C. W. Beebe, who succeeded in 

 rearing a young bird from the egg, noticed that its method of swim- 

 ming was by alternate strokes, and only when a sudden spurt was 

 desired were both used simultaneously. A captive bird kept in the 

 New York aquarium, in a pool twenty-eight feet long and three feet 

 deep, also swam under water with its wings closely folded, never in 

 use ; but Mr. Beebe, who has had unusual opportunities of watching 

 these birds, distinctly states that they do use their wings at times of 

 emergency to turn quickly, or to get up a burst of speed. 2 This has 

 been confirmed by so many observations made on birds in a wild state, 

 that the statement made by Mr. A. H. Evans in the Cambridge Natural 

 History, that Grebes and Divers "when submerged do not use the 

 pinions," can no longer be maintained 3 as an invariable rule. In the 

 case mentioned by Saxby, in which a wounded bird towed a boat, the 

 wings were used, and Messrs. Brewster and F. H. Allen record similar 

 cases ; but the normal mode of progression is no doubt by means of 

 the feet alone. 



Observation has shown that this Diver travels more rapidly under 

 water than on the surface. Mr. C. W. Townsend noticed that a bird 

 which heard the note of a companion immediately dived in the direc- 

 tion of the sound, and after appearing for a moment, dived again 

 almost at once and repeated the process till he reached his companion. 

 On another occasion one was seen chasing some Mergansers under 

 water. The distance which can be covered in this way varies as a 

 rule from two hundred to five hundred yards, or even half a mile 



1 J. Tomisou, Annals Scot. Nat. Hist., 1907, p. 31. 

 J The Auk, 1909, p. 235. 



3 The Cambridge Natural History: Birds, vol. ix. p. 52. A similar statement is also made 

 by Professor Lloyd Morgan in Habit and Instinct, p. 69. 



VOL. IV. 3 L 



