1S88.] EDIBLE BIRDS'-NESTS IN BRITISH NORTH BORNEO. 109 



by me last July from North Borneo. They were taken from the 

 Tatalahan Caves on the west coast. 



The later geological formation of British North Borneo, superin- 

 cumbent on the granitic and older rocks is a slate composed of sandy 

 and muddy sediments with occasional intercalated zones of limestone. 

 In the caves found in these limestone deposits the Swifts make their 

 homes, and build the nests so much coveted by the Chinese. The 

 demand for these ingredients of gelatinous soup is constant among 

 the wealthier Chinese, and the supply is extremely Umited ; the pro- 

 duct is consequently of increasing value as a luxury. There are 

 three qualities of these nests : — 



1. The white nests, which are gathered before the bird has com- 

 menced to lay any eggs, and which are composed of a clear trans- 

 parent mucilaginous matter, with very few feathers mixed with them. 



2. The red or grey nests ^ which are partly mixed with feathers, 

 in which eggs are sometimes found, and which have to be cleared of 

 much extraneous matter. The part of the nest adhering to the 

 limestone is sometimes tinged with pink. 



3. The black nests, which are much mixed with feathers. Some- 

 times fledglings may be found therein. These nests have been over- 

 looked at the previous gathering, and have darkened or deteriorated 

 from exposure to water and to the atmosphere of the caves. The 

 partial decomposition of the mucous matter renders them the least 

 valuable. 



The following market-quotations of the birds' -nests are taken 

 from the 'British North Borneo Herald,' of 1st December, 1H87. 



The following are the names of the principal mountains contain- 

 ing caves to which the Edible Swift resorts for the purpose of 

 breeding, so far as they are yet known : — 



No. 10. Butong. 



„ 11. Bukit Malingai. 



„ 12. Pigton. 



„ 13. Bahalla. 



„ 14. Ulu Sembakong, 



„ 15. Waleigh-waleigh, Kiu- 



oram River. 



,, 16. Mantanani. 



left untaken for too long a period after they 

 have been built, the part or hinge adhering to the limestone first turns red, 

 then black, and finally the nest drops to the ground, oftentimes with young 



