134 THE STORY OF BIRD-LIFE. 



In Borneo and other places the caves in which 

 the swiftlets build are leased to the collectors for 

 a considerable 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. 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 oc- 

 cupants, form together a loathsome mass of 

 putrid water, reaching in a cave visited by 

 Colonel Legge in Ceylon to a depth of 30 feet. 

 Mr Harry Pryer found that in one of the great 

 caves of northern Borneo a pole thrust into the 

 guano to a distance of 18 feet did not reach the 

 bottom, and there was over the floor an average 

 accumulation varying from 5 to 15 feet, so that 

 it is evident that the caves inhabited by the 

 swiftlets must have been tenanted by these birds 

 for a very long period." 



Yet another swift's nest must be noticed here. 

 *' One of the most curious nests in the world," 

 writes Dr Sharpe, in his oft-quoted " Wonders of 

 the Bird- World," "is to be seen in the bird-gallery 

 at the Natural History Museum, and is the work 

 of Salvin's Swift {Panytila sandi-hieronymi) from 

 Guatemala. It is entirely composed of seeds, 

 but whether the bird gathers these from the 

 plants or catches them in the air as they are 

 blown by the wind, has not been observed. In 

 this way the scanty material for the nest of our 

 European swifts {A]ms ajms and A. melba) are 

 obtained, but in the Guatemalan species the nest 

 is of such huge size that it would take a very 



