172 THE WONDER OF LIFE 



show the nature of the migratory movement with an 

 accuracy proportionate to the number of data. The marks 

 may show an irregular diffusion over a wide area, which 

 would indicate the absence of well- defined paths ; or they 

 may show a definite strand or curve, which would indicate 

 one of the favourite paths. Thus Dr. Thienemann has been 

 able to trace the migration of the stork with considerable 

 precision. There is an autumnal movement from the north 

 to the south-east as far as South Africa ; and a vernal return 

 to the natal district, sometimes within a few miles of the 

 birthplace, was proved in some cases. The rings were 

 returned from Damascus, Alexandria, the Blue Nile, Rhode- 

 sia, and further south. One of the birds recorded from 

 the Kalahari desert, 8,600 kilometres from its northern 

 home, had been killed for food by a native, who threw it 

 away, as uncanny, when he caught sight of the ring. Two 

 young storks, nine months old, were found in Basutoland, 

 9,600 kilometres from home. 



In the same way it has been made clear that there is 

 among hooded crows, for instance, a great westward move- 

 ment in autumn, e.g. from Finland along the shores of 

 the Baltic, and that there is a subsequent curve towards 

 the South. This westward and then southward curve 

 seems to be true of many birds in North Europe. Certain 

 contingents seem to swerve southwards by the valleys 

 of the Rhine and the Rhone, and then across the Mediter- 

 ranean to North Africa. Other contingents seem to go 

 further westwards, crossing, it may be, by way of Heligoland 

 to the South of England, and thence across to France, 

 Spain, and Portugal, finally landing like the others in 

 North Africa. For some other birds, like the swallow 

 and the Red-Spotted Bluethroat, there is considerable 



