8o NATURAL HISTORY OF SELBORNE 



and every straggler invariably withdraws by the twentieth, 

 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 extra- 

 ordinary, they begin to retire still earlier in the most 

 southerly parts of Andalusia, where they can be in no ways 

 influenced by any defect of heat, or, as one might suppose, 

 defect of food. Are they regulated 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 hirundines 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 

 with 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 

 hirundinis\ and often wriggle and scratch themselves, in 

 their flight, to get rid of that clinging annoyance. 1 



Swifts are no songsters, and have only one harsh scream- 

 ing note ; yet there are ears to which it is not displeasing, 

 from an agreeable association of ideas, since that note 

 never occurs but in the most lovely summer weather. 



They never can settle on the ground but through acci- 

 dent ; and when down, can hardly rise, on account of the 

 shortness of their legs and the length of their wings : 

 neither can they walk, but only crawl ; but they have a 

 strong grasp with their feet, by which they cling to walls. 

 Their bodies being flat they can enter a very narrow 

 crevice ; and where they cannot pass on their bellies they 

 will turn up edgewise. 



1 On the 8th of August 1893, Mr. Walter Burton brought me a young Swift 

 which he had captured on the window-sill of his house at Hanwell. It was appar- 

 ently nearly driven mad by the worry of the parasites, and had been observed 

 previously flying up and down in front of the house, screaming in great distress. 

 [R. B. S.] 



