158 The Natural History 



At some certain times in the summer I had remarked 

 that swifts were hawking very low for hours together 

 over pools and streams ; and could not help inquiring 

 into the object of their pursuit that induced them to 

 descend so much below their usual range. After some 

 trouble, I found that they were taking phryga?iece, ephe- 

 ifierce^ and libellulce (cadew-flies, may-flies, and dragon- 

 fiies) that were just emerged out of their aurelia state. 

 I then no longer wondered that they should be so willing 

 to stoop for a prey that afforded them such plentiful and 

 succulent nourishment. 



They bring out their young about the middle or latter 

 end of July : but as these never become perchers, nor, 

 that ever I could discern, are fed on the wing by their 

 dams, the coming forth of the young is not so notorious 

 as in the other species. 



On the thirtieth of last June I untiled the eaves of 

 an house where many pairs build, and found in each 

 nest only two squab naked pulli : on the eighth of 

 July I repeated the same inquiry, and found they had 

 made very little progress towards a fledged state, but 

 were still naked and helpless. From whence we may 

 conclude that birds whose way of life keeps them per- 

 petually on the wing would not be able to quit their nest 

 till the end of the month. Swallows and martins, that 

 have numerous famiHes, are continually feeding them 

 every two or three minutes ; while swifts, that have but 

 two young to maintain, are much at their leisure, and do 

 not attend on their nests for hours together. 



Sometimes they pursue and strike at hawks that come 

 in their way ; but not with that vehemence and fury that 

 swallows express on the same occasion. They are out 

 all day long in wet days, feeding about, and disregarding 

 still rain : from whence two things may be gathered ; 

 first, that many insects abide high in the air, even in rain ; 

 and next, that the feathers of these birds must be well 

 preened to resist so much wet. Windy, and particularly 

 windy weather with heavy showers, they dislike ; and on 

 such days withdraw, and are scarce ever seen. 



There is a circumstance respecting the colour of swifts, 



