172 SWIFTS. 



before their congeners bring out their second broods. We 

 may here remark, that, as swifts breed but once in a summer, 

 and only two at a lime, and the other hirundines 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 

 tenth of August, and sometimes a few days sooner ; 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 extraordinary, they begin to retire 

 still earlier in the more southerly parts of Andalusia, where 

 they can be nowise 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 researches, 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 Mrundinis,* 

 and often wriggle and scratch themselves, 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 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 narrow crevice ; and where they cannot 

 pass on their bellies, they will turn up edgewise. 



The particular formation of the foot discriminates the swift 

 from all the British hirundines, and, indeed, from all other 



* Crater ina hirundinis of Olfera. Em 



