BIRDS 117 



teresting and easily observed. Many birds gather in flocks, 

 sometimes of very great size, preliminary to migrating. Black- 

 birds congregate and fly in vast armies sometimes miles in 

 length. Bluebirds and robins go in smaller parties, and by 

 shorter stages, resting here and there on the way. Ducks 

 and geese fly in marshalled flocks, and probably in longer 

 flights, although even they stop on the way in our northern 

 lakes. Many birds disappear quietly without attracting any 

 notice, except that they all seem to be gone, when we think 

 of them. Some fly by day, as the above mentioned, others 

 in the night, as is known by their disappearance between 

 days, and also from the observations of lighthouse-keepers. 



Where do the birds go? Many do not go further than 

 the Middle and Southern States. The bobolink, which is 

 found only in pairs here and there in the meadows in the 

 North, collects in great armies on its way and spends the 

 winters in the southern rice-fields along the coast of the Gulf. 

 The robins also go here for the winter. Some of our birds 

 go to Mexico, and even to South America. Some fly across 

 to the West Indies. 



It seems probable that birds are guided in their travels 

 by more than the sense of sight. They have a good sense of 

 direction, and often fly across the sea in foggy weather with- 

 out losing their way. Different species choose different 

 routes of migration. Sea fowl generally travel along the 

 coasts. Some of the land birds travel along the Atlantic 

 Coast and then fly across from Florida to the West Indies, 

 and from there to the shores of South America. Their route 

 seems to be governed by the food supply. For most of the 

 species that fly via the West Indies do not use the Lesser 

 Antilles as stepping-stones, as here the food supply would 



