The Fairy Martins 199 



able for the long neck which the birds attach to them, 

 and they are often found in large numbers clustered to- 

 gether on a rock. In India a colony of the Indian Cliff- 

 Swallow, as it is popularly called (Petrochelidon fluvicola\ 

 has been known to construct six hundred nests, and 

 large gatherings are also seen in the allied Australian 

 species (P. ariel}, as well as in the South African Cliff- 

 Swallow (P. spiloderd) and the North American species 

 (P. pyrrhonotri}. The nests are attached to the side of a 

 cliff or building, and have also been found on the side of a 

 large barn in North America. Gould says that in the case 

 of the Australian Cliff-Swallow or Fairy Martin the nest is 

 constructed by several birds working together, one remain- 

 ing inside the nest and receiving the pellets as they are 

 brought by its companions. The spouts are often eight or 

 nine inches in length, and are not always built in the same 

 direction, but take different angles. 



The nests of the Edible Swiftlets (Collocalia) are also 

 most curious structures. With these nests a large trade is 

 done with China, from many of the Malayan Islands, over 

 three and a half million nests having been known to be 

 exported in a single year from Borneo to the latter 

 country, where birds'-nest soup is considered a delicacy. 

 In Borneo and other places the caves in which the 

 Swiftlets build are leased to the collectors for a consider- 

 able sum, but it is only the white nests, made of the 

 pure secretion derived from the salivary glands of the 

 birds, which are of any real value. The nests of those 

 species which mix into their nests grass or feathers are 

 not appreciated as an article of commerce. Quantities 

 of guano are also found in some of the caves, formed 

 by the debris from the nests, the bodies of young birds 

 which have perished, and the droppings of hundreds 

 of occupants, which form together a loathsome mass of 

 putrid water, reaching, in a cave visited by Colonel Legge 



