But in nothing are swifts more singular than in 

 their early retreat. They retire, as to the main body 

 of them, by the loth of August, and sometimes a 

 few days sooner : and every straggler invariably 

 withdraws by the 20th, 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 begin to retire still earlier in the 

 most southerly parts of Andalusia, where they can 

 be no ways influenced by any defect of heat; or, as 

 one might suppose, defect of food. Are they regu- 

 lated in their motions with us by a failure of food, 

 or by a propensity to moulting, or by a disposition 

 to rest after so rapid a life, or by what ? This is one 

 of those incidents in natural history that not only 

 baffles our searches, but almost eludes our guesses ! 



These hiriindines never perch on trees or roofs, 

 and so never congregate with their congeners. 

 They are fearless while haunting their nesting-places, 

 and are not to be scared by a gun ; and are often 

 beaten down with poles and cudgels as they stoop to 

 go under the eaves. Swifts are much infested with 

 those pests to the genus called hippoboscce {Anaperce 

 hirundmis, Leach), and often wriggle and scratch 

 themselves, in their flight, to get rid of that cling- 

 ing annoyance. 



38 



