BIRDS. 457 



they had migrated to warmer climes, and so returned 

 again for one day. Is it not more probable that they 

 are awakened from sleep, and like the bats are come 

 forth to collect a little food? Bats appear at all seasons 

 through the autumn and spring months, when the ther- 

 mometer is at 50, because then moths, Phalcence, are 

 stirring. 



These swallows looked like young ones fs . 



WAGTAILS. 



WHILE the cows are feeding in moist low pastures, 

 broods of wagtails, white and gray, run round them 

 close up to their noses, and under their very bellies, 

 availing themselves of the flies that settle on their legs, 

 and probably finding worms and larvce that are roused 

 by the trampling of their feet. Nature is such an ceco- 

 nomist, that the most incongruous animals can avail 

 themselves of each other! Interest makes strange 

 friendships 19 . 



18 Of their migration the proofs are such as will scarcely admit of a 

 doubt. Sir Charles Wager and Captain Wright saw vast flocks of them 

 at sea, when on their passage from one country to another. Our author, 

 Mr. White, saw what he deemed the actual migration of these birds, and 

 which he has described in his History of Selborne*: and of their con- 

 gregating together on the roofs of churches and other buildings, and on 

 trees, previous to their departure, many instances occur; particularly I 

 once observed a large flock of house martins on the roof of the church 

 here at Catsfield, which acted exactly in the manner here described by 

 Mr. White, sometimes preening their feathers and spreading their wings 

 to the sun, and then flying off all together, but soon returning to their 

 former situation. The greatest part of these birds seemed to be young 

 ones. MARKWICK. 



The best proof of actual migration is drawn from the American swal- 

 lows which Audubon actually traced from the north to Florida, and saw 

 them the whole winter through at New Orleans, whence they departed 

 for the north again in spring. REN ME. 



19 Birds continually avail themselves of particular and unusual cir- 

 cumstances to procure their food ; thus wagtails keep playing about the 

 noses and legs of cattle as they feed, in quest of flies and other insects 

 which abound near those animals ; and great numbers of them will follow 



* Letter XXIII. to Pennant, p. 118. 



