158 THE NATURAL HISTORY 



flight, they raise their wings, and make them meet over 

 their backs. 



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 phryganeae, ephemerae, and libellulae 

 (cadew-flies, may-flies, and dragon-flies) that were just 

 emerged out of their aurelia state. I then no longer won- 

 dered 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 perpetually on the wing would not be able 

 to quit their nest till the end of the month. Swallows and 

 martins, that have numerous families, are continually feed- 

 ing 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. 



