SWALLOW AND HOUSE-MARTIN .'*. 



haul, without this expedient. thc\ aiv often forcrd to settle to pick up 

 their lurking prey/' an observation which supplies one of the reasons 

 why the species cannot limit their Held ofcha.se to the air. 



The same writer notes that when a fly is taken by a swallow 

 in the air, " a smart snap from her bill is heard, resembling the noise 

 aft the shutting of a watch-case ; but the motion of the mandibles are 

 too quick for the eye." Seeing the motion of the mandibles depends 

 on the 1 1 istance, no doubt, and also the quickness of the eye. Another 

 observer had the good fortune to be able one day to watch swallows 

 flying backwards and forwards very close to him, so close, indeed, 

 that he could distinguish the details of their plumage. " Not one flew 

 with open mandibles or outstretched neck. . . . But every now and 

 then a sweep to the right, a jerk to the left, a leap upward or a plunge 

 downward, indicated the close pursuit of prey, and a rapid gape of the 

 jaw its inevitable capture." 1 The sudden turns to right or left, 

 upward or downward, may be witnessed without difficulty even at 

 some yards distance in the case of both species. No doubt the martin 

 also captures its victims in exactly the same way. 



When the insect is once in the mouth, its chances of escape are 

 small, even though the beak may be opened several times in succes- 

 sion to admit other insects, and none be swallowed ; for each, when 

 the mandibles close behind it, finds itself adhering to a " profuse 

 clammy secretion," to quote Macgillivray, who noticed that half a 

 dozen insects or more might be found so caught in the mouths of 

 swallows he shot. This was the case before the birds had young to 

 feed, a fact which shows that they do not always trouble to swallow 

 each insect separately. 



Neither swallows nor martins are content merely to snap up small 

 insects, but seize large moths and butterflies as well ; sometimes, accord- 

 ing to one observer, separating the wings from the body, and letting the 

 former drop to the ground. 2 This, however, is not a necessary pre- 



> Xooloffitt, 1805. 073) (C. W. Bevis). 



* A. H. Patterson, in hia Wild Life in a Norfolk Entuary (p. 217), quote* from letters of 

 various observers both with respect to the fact that large moths and butterflies are caught. 



