FOR NORTHERN INDIA 173 



migrants are noticed in the calendar for 

 December. 



In October the annual moult of the birds 

 is completed, so that, clothed in their warm 

 new feathers, they are ready for winter some 

 time before it comes. In the case of the red- 

 start, the bush-chat, most of the wagtails, 

 and some other species, the moult completely 

 changes the colouring of the bird. The reason 

 of this is that the edges of the new feathers are 

 not of the same colour as the inner parts. 

 Only the margins show, because the feathers 

 of a bird overlap like slates on a roof, or the 

 scales of a fish. After a time the edges of the 

 new feathers become worn away, and then the 

 differently-hued deeper parts begin to show, so 

 that the bird gradually resumes the appearance 

 it had before the moult. When the redstarts 

 reach India in September most of the cocks 

 are grey birds, because of the grey margins to 

 their feathers ; by the middle of April, when 

 they begin to depart, many of them are black, 

 the grey margins of the feathers having com- 

 pletely disappeared ; other individuals are 

 still grey because the margins of the feathers 

 are broader or have not worn so much. 



October is the month in which the falconer 



