NA TURA L HIST OR Y OF SELB ORNE. 1 79 



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, failure of food. Are they regulated in their 

 motions with us by a defect 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 con- 

 gregate 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 



WHITS-BELLIED SWIFF. 



the eaves. Swifts are much infested with those pests to the genus 

 called hippoboscce hirundinis, and often wriggle and scratch them 

 selves in their flight to get rid of that clinging annoyance. 



Swifts are no songsters, and have only one harsh screaming 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 accident ; 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 



