LXII.] 
OF SELBORNE. 
their way ; but not with that vehemence and fury tliat 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 repecting tlie colour of swifts wliich 
seems not to be unworthy our attention. When they arrive in the 
spring they are all over of a glossy, dark, soot-colour, except 
their chins, wdiich are white ; but, by beiug 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 perliaps retire to 
rest for a season, and at that juncture moult and ('hange 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 
hirnndines breed invariably twice. It is |)ast all doul;>t tliat 
swifts can breed but once, since they withdraw in a short time 
after the flight of their young, and some time before their con- 
geners 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 hirundine>^ 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 lUth 
of August, and sometimes a few days sooner : and every 
straggler invariably withdraws by the 20th, while their con- 
geners, 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 
