Ii6 THE MIGRATIONS OF BIRDS 



in length between its summer and its winter resi- 

 dence. (See Fig. 3.) It has been truly remarked that 

 this tern probably experiences more daylight than 

 any other living creature, since it lives in regions 

 where the midnight sun is its constant companion in 

 both north and south, and only in travelling does it 

 encounter any extended periods of darkness. 



Many birds nest in the northern United States 

 and Canada and pass south toward the Gulf of 

 Mexico to winter. As well-known examples may 

 be cited such winter residents as the white-throated, 

 white-crowned, and tree sparrows, j uncos, brown 

 creepers, golden-crowned kinglets and robins, with 

 hordes of grackles, redwings, and cowbirds among 

 our smaller birds, and various species of ducks, the 

 woodcock, and many others, among larger ones. 

 Such migrants include the hardier species, some of 

 whose individuals may linger in protected places 

 well within the reach of severe cold. 



Many of our small birds travel much greater dis- 

 tances for no apparent reason. Many species of 

 wood warblers nest in the northern United States 

 and Canada, and fly in winter to the West Indies, 

 leaving perhaps a few of their individuals to linger 

 in the southern states. Black and white warblers 

 range in winter season from extreme southern 

 Georgia southward into the West Indies; some, un- 

 dismayed by broad waters, cross to Venezuela and 



