NATURAL HISTORY OF SELBORNE. 177 



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 

 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 nest 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 

 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 



