178 PASSENGER TURTLE. 



unlike those of other birds, whose movements are 

 considerably affected by temperature, are not under- 

 taken, at any fixed period or season of the year, or 

 frozen or cold, to a warmer climate, but are entirely 

 regulated by the supply or want of food ; for Audu- 

 bon, in his interesting account of this bird, remarks, 

 " It sometimes happens, that a continuance of a suf- 

 ficient supply of food in one district will keep these 

 birds absent from another for years. I know at 

 least to a certainty, that, in Kentucky, they re- 

 mained for several years constantly, and were no 

 where else to be found. They all suddenly disap- 

 peared one season, when the mast was exhausted, 

 and did not return for a long period." 



Their power of flight, indicated by the length of 

 their wings and tail, is very great ; and, indeed, with- 

 out a locomotive gift of extraordinary extent, it 

 would be impossible for such countless numbers as 

 are seen associated together to exist ; for the supply 

 of food in the immediate neighbourhood of their 

 roosting resort or their breeding-places, when they 

 are necessarily engaged for months together, soon 

 becomes exhausted, and they have frequently to tra- 

 verse each day an immense distance in quest of a 

 further supply. This is proved by facts narrated by 

 Wilson in his graphic history of this bird, as well as 

 by Audubon, who mentions the extraordinary cir- 

 cumstance, that " pigeons have been killed in the 

 neighbourhood of New York, with their crops full of 

 rice, which they must have collected in the fields of 



