i6o GLIMPSES OF INDIAN BIRDS 



It is a universal rule that all migratory birds of the 

 Northern Hemisphere breed in the more northerly 

 of their two homes. This seems to indicate that they 

 were formerly permanent residents in the latter. 

 Geology tells us that thousands of years ago the cHmate 

 of this earth suddenly became colder. The result 

 was that the more northerly portions of it were ren- 

 dered uninhabitable for birds during the winter — the 

 frost killed insect life and the snow made vegetable 

 food difficult to procure ; hence, the birdfolk were 

 confronted with the alternative of starving in winter 

 or going south in search of food. They chose the latter 

 alternative. So powerful is the ''homing instinct" — 

 the instinct that man has developed so wonderfully 

 in the homer pigeon — that these migrants invariably 

 returned in the summer to their old homes for breeding 

 purposes. 



The cHmate has again become milder, so that for 

 many migratory birds migration is no longer necessary ; 

 nevertheless, they still perform the double journey 

 every year. The force of habit is strong in birds. 

 Those AustraHan finches which are imported into 

 India, even when kept in aviaries in the Himalayas, 

 nest in December and January as they did in AustraHa, 

 where these are summer months. 



The ducks and geese that visit the Punjab in winter 

 are too numerous to be dealt with in this brief essay, 

 which of necessity is not exhaustive. It merely deals 

 with such of the winter visitors to the Punjab as are 

 seen every day. Every winter Northern India is 

 invaded by millions of grey-lag and barred-headed 



