THE SPARROW KIND. 285 



These are chiefly the latter weakly broods, which 

 are not yet in a condition to set out. They are 

 sometimes even too feeble to venture till the set- 

 ting in of winter, while their parents vainly ex- 

 hort them to efforts which instinct assures them 

 they are incapable of performing. Thus it often 

 happens that the wretched little families, being 

 compelled to stay, perish the first cold weather 

 that comes ; while the tender parents share the 

 fate of their offspring, and die with their new- 

 fledged brood. 



Those that migrate are first observed to arrive 

 in Africa, as M. Adanson assures us, about the 

 beginning of October. They are thought to have 

 performed their fatiguing journey in the space of 

 seven days. They are sometimes seen, when in- 

 terrupted by contrary winds, wavering in their 

 course far off at sea, and lighting upon whatever 

 ship they find in their passage. They then seem 

 spent with famine and fatigue; yet still they 

 boldly venture, when refreshed by a few hours 

 rest, to renew their flight, and continue the course 

 which they had been steering before. 



These are facts proved by incontestable autho- 

 rity ; yet it is a doubt whether all swallows mi- 

 grate in this manner, or whether there may not 

 be some species of this animal that, though exter- 

 nally alike, are so internally different, as to be 

 very differently affected by the approach of win- 

 ter. We are assured from many, and these not 

 contemptible witnesses, that swallows hide them- 

 selves in holes under ground, joined close to- 

 gether, bill against bill, and feet against feet. 



