64 THE STORY OF BIRD-LIFE. 



a lifetime in observing bird-life in Heligoland, 

 believed that the Arctic blue-throat can leave 

 Africa at dusk one evening, and arrive in Heligo- 

 land nine hours after, travelling 1600 miles dur- 

 ing the night, which gives, as Dr Sharpe mildly 

 comments, "the almost miraculous velocity of 

 180 miles per hoar." This is a prodigious per- 

 formance to assign to little birds of the size of 

 our robin. 



This same authority (Gatke), by the way, in 

 estimating the time taken by plovers and cur- 

 lews in the flight from Heligoland to oyster- 

 beds, some four English miles distant, calculated 

 that they accomplished this distance in one 

 minute, or at the rate of 240 miles an hour ! ! 



The speed and power of the flight depend upon 

 the size of the muscles which m.ove the wings. 

 These muscles are of great size, and familiar to 

 us all in the shape of the breast of the fowl or 

 duck, for instance. The weight of these in rela- 

 tion to all the rest of the muscles put together 

 varies. Mr Headley found that in pigeons they 

 represented just about one-fifth of the total 

 weight. For the purpose of attachment of these 

 muscles, the breast-bone in these, and in all birds 

 that fly, has developed an enormous plate of bone 

 called a keel, from its resemblance to the keel of 

 a ship, the hull being representtd by the body 

 of the breast-bone. 



There are one or two points concerning the 

 wings of nestling birds that are well worth 

 noting. 



In South America there lives a bird called the 

 hoatzin, about which we are still puzzled. Its 



