1 78 NA TURAL HIST OR Y OF SELBORNE. 



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, feed- 

 ing 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, which 

 seems not to be unworthy of our attention. When they arrive in 

 the spring, they are all over of a glossy, dark soot colour, except 

 their chins, which are white ; but, by being all day long in the sun 

 and air, they become quite weather-beaten and bleached before 

 they depart, and yet they return glossy again in the spring. Now, 

 if they pursue the sun into lower latitudes, as some suppose, in order 

 to enjoy a perpetual summer, why do they not, return bleached? 

 Do they not rather perhaps retire to rest for a season, and at that 

 juncture moult and change their feathers, since all other birds are 

 known to moult soon after the season of breeding ? 



Swifts are very anomalous in many particulars, dissenting from 

 all their congeners not only in the number of their young, but in 

 breeding but once in a summer ; whereas all the other British 

 hirundines breed invariably twice. It is past all doubt that swifts 

 can breed but once, since they withdraw in a short time after the 

 flight of their young, and some time before their congeners bring 

 out their second broods. We may here remark that, as swifts 

 breed but once in a summer, and only two at a time, and the other 

 hirundines twice, the latter, who lay from four to six eggs, increase 

 at an average five times as fast as the former. 



But in nothing are swifts more singular than in their early retreat. 

 They retire, as to the main body of them, by the tenth of August, 

 and sometimes a few days sooner ; and every straggler invariably 

 withdraws by the 2oth, while their congeners, all of them, stay till 

 the beginning of October ; many of them all through that month 

 and some occasionally to the beginning of November. This early 

 retreat is mysterious and wonderful, since that time is often the 

 sweetest season in the year. But what is more extraordinary, they 



