462 ANIMAL LIFE-HISTORIES 



The glands of the mouth, which are so often of importance 

 in nest-building on account of their sticky secretion, are par- 

 ticularly well-developed in Swifts (Cypselida)> birds which are 

 often erroneously mistaken for Swallows. In our Common Swift 

 (Cypselus apus) this secretion is used to glue straw, dry grass, 

 and the like, into a flattish nest, which is built in some hole or 

 cranny. A lining of feathers is added. A kind of Swift (Panyp- 

 tila Sancti Hieronymi) native to Guatemala glues seeds together 



Fig. 984. Edible Nests of Collocalia 



into a long hanging nest, shaped something like a knobbed 

 walking-stick. The entrance is at the lower end, and the eggs 

 are lodged in the " knob " at the top. Perhaps the most re- 

 markable of all bird's nests, so far as the building material is 

 concerned, are those which the Chinese prize as an article of 

 diet. They are constructed by certain Swifts (species of Collo- 

 calia, fig. 984) which range from Madagascar eastwards to the 

 Marquesas Islands. In form they resemble those of the Swallow, 

 but are entirely composed of the sticky fluid secreted by the 

 glands of the mouth, with an occasional admixture of other 

 substances. They are mostly to be found in caves. 



