174 TEXT-BOOK OF ZOOLOGY 



beginning of May, and departs again in August. It is a very active bird, 

 a true denizen of the air, darting about from early dawn to late dusk at 

 immeasurable heights or close above the ground or the water. (The 

 wings are very long and sickle-shaped, and the tail deeply notched.) 

 Its food consists of small insects, which it captures on the wing. (The 

 beak is short, but the gape of the mouth extends as far as under the 

 eyes.) It never descends voluntarily to the ground, its weak legs neither 

 permitting it to walk nor to hop. By means of its sharply-clawed toes, 

 however, all of which are directed forwards (clinging feet), it manages 

 to hook itself on to walls and palings. The nest is a rough structure of 

 straws, feathers, and poplar catkins, snatched by the bird while on the 

 wing, and cemented together by a sticky saliva. It is usually placed in 

 the crevice of a wall or cliff or in the hole of a tree. 



The Salanganes (Collocalia) are birds which closely resemble the 

 swifts. They construct basin-shaped nests from a viscid indiarubber- 

 like saliva, which rapidly hardens in the air. These nests are intro- 

 duced into commerce as " edible swallows' nests." The home of these 

 birds is in the East Indian Islands. 



The Common Nightjar or Goatsucker (Caprimulgus europaus) is 

 nocturnal in its habits, like the owl (which see), and insectivorous, 

 capturing its prey on the wing, like the swallow (which see). Hence, in 

 the structure of its body the bird bears resemblances to both these 

 species. Its plumage, like that of the owl, is uncommonly soft, which 

 renders the flight of the bird noiseless, while the wings, like those of 

 the swallow, are long and pointed, and adapt it for nimble and rapid 

 flight. (Why are both these conditions necessary ?) Its large eyes and 

 acute hearing enable it, like the owl, to hunt at dusk and in the dark. 

 Being of larger size than the swallow (about the size of a blackbird), a 

 diet of gnats and flies would not satisfy its needs. Its food, in fact, 

 consists of large beetles and, preferably, moths. Its beak, however, is 

 too small to grasp insects of this size, whence the gape of the mouth 

 extends as far as under the eyes, and the throat is very wide. The oral 

 opening is further considerably enlarged by the presence of bristle-like 

 feathers (vibrisscs) at the upper edge of the large mouth, which is used 

 after the fashion of a butterfly-net. The bird is almost incapable of 

 walking on account of its weak feet (see swallow). When at rest, it 

 lies flat on the ground or upon a branch lengthwise, its short toes not 

 allowing it to clasp the latter. In this position, or when sitting on its 

 brood, the bird cannot be distinguished from a piece of bark or the dry 

 leaves which cover the soil, on account of the dull colour of its plumage, 

 which is grey and brown, with darker and lighter stripes, spots, and 

 undulating lines (compare owl). Though in many ways a very peculiar 



