REDTHROATED-DIVER 457 



Divers, the flight feathers of both wings are all moulted simultaneously, 

 probably in a single day, so that for a short time about the end of 

 September or early in October the power of flight is completely lost. 1 

 To birds so much at home on and under the water this is almost 

 a matter of indifference, for besides man they have few enemies. 



There is one strange feat which they occasionally perform on the 

 wing and which deserves mention. When flying at a great height they 

 will descend rapidly, twisting and turning as they hurl themselves 

 earthward, and the rush of air through the primaries causes a sound 

 not unlike the roar of a train, and so disproportionate to the size of 

 the bird, that those who hear it for the first time can scarcely be 

 brought to believe that the sound is really caused by it. 2 



1 See W. Farren, Annals Scot. Nal. ///*/., 1809, p. 114. 

 a Home Life of some Marsh Birds, p 34. 



