THE SWIFTS. 



143 



the usual twelve, and in the case of the commonest species 

 by the fact that the first toe is not directed backwards 

 as in the Swallows ; all the four toes spreading out like 

 the fingers of the hand, or falling into right and left pairs. 



As far as their habits are concerned, Swifts differ from 

 Swallows, in most cases, by never settling on the ground 

 or trees, etc. They do not perch or walk, but can cling or 

 climb well enough, their claws being very strong and sharp. 

 Their nests are built of various materials, stuck together 

 by the abundant and viscid saliva of the birds, and the 

 " edible bird's nests," so dear to the Chinese in more senses 

 than one, are made by a small Swift (Collocalia francica) 

 found in some localities on our coasts among other places, 

 which uses nothing but the saliva in the construction, 

 this drying into a substance like isinglass. The eggs of 

 all Swifts are long and white. 



Young Swifts are hatched naked, and fledge of! into a 

 plumage much like that of their parents. These seldom 

 differ in plumage according to sex, nor has the male 

 any sing. They are not particularly interesting as birds 

 go, but two are so common that they deserve notice 

 here. 



THE HOUSE-SWIFT (Cypselus affinis) is well over five 

 inches long, and has a short square-ended tail ; its plum- 

 age is sooty-black with a conspicuous white patch on the 

 back and the throat also white. Young birds are almost 

 exactly like the old ones. 



This bird is found almost all over Africa and India, but 

 east of the latter country is replaced by a blacker species 

 with the tail rather longer and slightly forked (Cypselus 



