INTRODUCTION. 7 



How astonishing is the instinct which induces 

 these little creatures to emigrate to other coun- 

 tries, when the season approaches in which the 

 food they require is no longer to be found in the 

 land where they have built their nests, and reared 

 their young, and sung their sweetest songs! 

 How amazing the skill with which they pursue 

 their distant journies to precisely those countries 

 which are the best furnished with means for 

 their support! Equally wonderful is their re- 

 turn, at stated periods, to the shores they have 

 quitted. Well may we exclaim, with the de- 

 lightful naturalist of Selborne, 



" Whence your return by such nice instinct led, 

 When spring, soft season, lifts her bloomy head ? 

 Such baffled searches mock man's prying pride 

 The God of nature is your secret guide." 



We cannot willingly close this little sketch 

 without quoting the appropriate and elegantly 

 written observations of a naturalist of the present 

 day. " Birds, generally speaking, appear to 

 belong more to the air than to the earth: they 

 constitute moving republics, which traverse the 

 atmosphere at stated periods in large bodies. 

 These bodies perform their aerial evolutions like 

 an army, crowd into close column, form into 

 triangle, extend in line of battle, or disperse in 



