On the Migration of North American Birds. 97 



anticipation of this season) that birds assemble, in troops, to set out 

 on their annual aerial voyage to southern climes. The young in 

 most species instinctively flock together as if disdaining to enquire 

 the path of migration from the old. Some taught by an instinct of. 

 nature, which way to bend their course depart singly, and make 

 their long and weary journey alone, others go in straggling flocks, 

 sometimes you see the air almost darkened with the swallows and 

 night hawks, ( Caprimulgus Virginia?ius,) other species crowd into 

 close columns during their flight. This is particularly the case with 

 the wild pigeons, wax birds, (Bomhycilla Carolinensis,) black birds, 

 (Icterus Phoenicus } ) the cow bunting, (J. Pecoris,). the wild geese, 

 ducks and several species of Tringas or sand birds. Some species move 

 slowly and seem only urged along either by the cold or by a scarcity of 

 their accustomed food. Others pass rapidly and effect their migra- 

 tion in a very few days. Some flit along the earth's surface and rest, 

 here and there, as if to take a glance at the fields, gardens and habi- 

 tations of man, whilst others mount high in the air and soar almost 

 among the clouds as if scarcely deigning to cast an eye on the cities 

 and villages and the puny efforts of their inhabitants and on the 

 mountains and vallies beneath them. These aerial voyagers, by an 

 admirable instinct, seize upon a favorable moment in which winds 

 and the weather are fitted for these migrations ; they are not carried 

 along by the wind, but are obliged from the construction of their 

 feathers to fly against it. They have a foreknowledge of frosts and 

 snows for weeks before they arrive and they have a mysterious but 

 sure monitor within them to tell them the coming of spring. They 

 require no chart and no compass to enable them to navigate the air and 

 pass through the region of clouds, the thunder and the storm. They 

 arrive at the end of their destined voyage, and there in the grove, 

 the forest, the mountain, the field or the garden, they find food, shel- 

 ter and a home prepared by the hand of providence ; there in all prob- 

 ability, they revisit the very neighbourhood and probably build their 

 nests in or near the same tree, or bush, or tuft of grass in which the 

 year before they reared their young. This too may have been the 

 scene of their infancy and here they may have carroled their earliest 

 song. The disposition of birds to revisit, annually, the place where 

 they have once bred is remarkable. A blue bird that was marked 

 so as to be known, built its nest, for ten successive years, in a box 

 that had been prepared for the purple martin* A pewee, (Musci- 

 capafiisca,) has been known to revisit the same cave for nine sue- 

 Vol. XXX.— No. 1. 13 



