WILD LIFE OF ORCHARD AND FIELD 



delayed, although, like a late train on a clear track, 

 they can " make up time " very fast when the route 

 is open. Similarly the inland birds may be halt- 

 ed by chilling northerly storms, which now and 

 then descend upon us after the migration has 

 begun, and check it completely. Searching the 

 woods and fields, you will find bird-life storm-bound, 

 and not a new feather greets you as long as the 

 bad weather lasts. Then some evening the wind 

 changes, blows balmy from a southerly direction, 

 and next morning the sunny woods will be full of 

 birds a choir of music where the day before 

 were almost silence and solitude. These are the 

 avant courriers of the host that has been waiting, 

 and which has come on in the night, perhaps from 

 a long distance and at high speed. All the king- 

 birds in the central Mississippi Valley were once 

 known to make a rush forward of two hundred 

 miles in a single night. 



Such sudden accessions of migratory birds are 

 called " waves," and they follow one another irreg- 

 ularly, coinciding with the alternating "waves" 

 of cold-wet and warm-dry weather that compose 

 our spring climate. 



The actual travelling seems to be done mainly at 

 night. Early risers by the sea will observe long lines 



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