198 THE MIGRATIONS OF BIRDS 



the north during early June in a line of flight that 

 carried them up the valley of the Big Horn River. 

 It would seem that they may have followed west 

 along the valley of the Yellowstone from the region 

 of the Plains, and then turned off into the valley of 

 the Big Horn, which flows to the north, so that the 

 final portion of their spring migration carried them 

 directly south to their breeding area. 



The migration flights of the bobolink possess 

 considerable interest, since the actual limits of the 

 winter home of this species were for some time 

 uncertain. The birds come north in spring, arriving 

 in middle latitudes in late April or early May, with 

 the males in handsome, pied summer plumage. 

 With the settlement of the west it appears that this 

 species has greatly increased in numbers in that 

 section, if it has not actually extended its range, as 

 in the Gallatin valley and similar areas in north- 

 western Montana it is now common, though form- 

 erly it was very local in occurrence. After breeding 

 in northern meadows and hay-fields, where the 

 musical songs and handsome appearance of the 

 males endear them to all, these birds in late summer 

 resort to marshes and grassy swales, where they pass 

 through a moult in which the males assume a dull 

 streaked plumage like that of their mates. 



Southward migration begins about the middle of 

 August, with August 1 8 as the average date of arri- 



