NO. 2298. 



THE GUANO BIRDS OF PERU—COKER. 



501 



10 years before and was not worked afterwards until the season of 

 1906. During two years there were removed m all something over 

 3,000 tons. If this information is correct, this guano was deposited 

 durmg a period of 10 years, and at the average rate of 300 tons a 

 year. This is on the supposition that the island was really cleaned 

 10 years before, though it is probable that it was not cleaned then 

 with the same thoroughness with wliich islands are swept now. 



The guano was different in appearance and odor from that of birds, 

 an abundance of hair being especially noticeable. There was an 

 enormous quantity of skeletons and skins of lobos, many of which 

 perhaps had been left on the island when it was last cleaned of guano. 

 Although, except for the hairs and bones, it was largely pure manure 

 (with only 8 per cent of sand), there was scarcely any odor of am- 

 monia. The color was brown to black and somewhat greasy. 



Analyses of two samples of guano taken from different places on 

 this island, as made by l^ir. H. H. Bunting, chemist of the Peruvian 

 Corporation, are given in the first two columns of the following table: 



Moisture 



Sand 



(o) Organic matter 



(6) Phosphoric acid 



Alkali, salts, etc 



(a) Containing nitrogen 



Equal to ammonia 



(6) Equal to tricalcie phosphate 



(1) "Sea- 

 lion 

 guano," 

 CerroAzul. 



29.40 

 8.22 

 17.74 

 16.80 

 27.84 



(2) "Soa- 



lion 



guano," 



CerroAzul. 



100.00 

 2.86 

 3.47 



30.67 



23.40 

 8.05 

 IS. 86 

 19. 88 

 29.81 



100.00 



3.21 



3.89 



43.41 



(3) "Sea- 

 Uon 



guano," 

 Lobos de 



Afuera. 



8.32 



1.15 



48. 43 



16.89 



25.21 



100.00 



7.90 



9.59 



36. 87 



(4) •• Sea- 

 lion 

 guano," 

 Pure sea- 

 lion faeces. 



43. 96 

 .40 

 18.94 

 16.34 

 20.36 



100.00 



2.33 



2.83 



35.67 



The presence of some feathers suggested a degree of participation 

 by birds in forming the deposit, but the low nitrogen value proves 

 that the part of birds was inconsiderable. 



Another small island, in the Lobos de Afuera group, contained a 

 deposit of mixed lobo and bird guano, the high proportion of nitro- 

 gen indicating a substantial proportion of bird guano. The analysis 

 is given in the third colunm of the table of analyses. 



The latter deposit had been formed in a more humid climate 

 (Lobos Island) than the other (Cerro Azul), so that the guano would 

 naturally have suffered more deterioration; yet the nitrogen content 

 was higher and there was other reason to suspect that birds had 

 contributed to the formation of the deposit. In order to ascertain 

 just what was the nature of the fresh lobo guano unmixed with that 

 of bird, several portions of fresh faeces were taken and mixed to form 

 one sample, which was dried, bottled, and analyzed. The result is 

 shov/n m the fourth column. The nitrogen figure is even lower than 

 the samples taken from the beds at Cerro Azul, but after allowance 



