THE SWIFT'S. 143 
Externally, Swifts may be distinguished from Swallows 
by the fact that they have only ten tail-feathers instead of 
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 off into a 
plumage much like that of their parents. These seldom 
differ in plumage according to sex, nor has the male any 
song. They are not particularly interesting as birds go, 
but two are so common that they deserve notice here. 
THE HovusE-Swirt (Cypselus affinis) is well over five 
inches Jong, 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 
