232 MIGRA TION. 



The time of arrival, as also of departure, though so 

 exact in each case, varies greatly with different species. 

 The Robin, the Bluebird, the various Blackbirds, the 

 Phoebe, the Killdeer, the Meadow Lark and the Song 

 Sparrow arrive before winter is over, and are thus the har- 

 bingers of spring; but Thrushes, Warblers, Cuckoos, and 

 the Flycatchers generally, come with the spring flowers and 

 the tender foliage. "The Indian of the fur countries, in 

 forming his rude calendar, names the recurring moons 

 after the Birds-of -passage, whose arrival is coincident with 

 their changes." 



Those birds which arrive first stay latest, and the latest 

 visitants are the first to depart. For the most part, the 

 males are the first on the ground in the spring, while the 

 females or- the young lead the van in the fall; and it is 

 pretty certain that those individuals spending the summer 

 farthest north also winter farther north than those of the 

 same species which do not reach such high latitudes. It 

 may also be set down as a general law that those species 

 which spend the summer farthest north also winter farthest 

 south. 



Many kinds of birds, especially such as fly high and 

 encounter but slight danger, perform their passage in part 

 or wholly by day; but those passing near the ground, or 

 experiencing special dangers by the way, almost invariably 

 move under cover of the night. It is probable that the 

 divers such as Loons and Grebes make their passages 

 mostly in the water, following the great water-courses; 

 while certain running birds, as the Rails, achieve a great 

 part of their journey a-foot. 



Our North American birds seem to migrate year after 

 year in certain lines, toward the north in the spring, and 

 again toward the south in autumn. For instance, of the 



