NO. 2298. 



THE GUANO BIRDS OF PERV—COKER. 



485 



be regarded as an asset representing a value of several millions of 

 dollars. 



Nor is this the only flock, although the prmcipal one of the coast. 

 Other important flocks were noted at the Lobos de Tierra Islands of 

 the North, at Asia, Pachacamac, and other places, besides the neigh- 

 boring flocks at the Baliestas Islands, and on outlying rocks. There 

 were four or five small islets about the North Chincha Island, each 

 with something hke 1,000 guanays. In 1907 the Baliestas North, 

 Middle, and South Islands, respectively, yielded about 500, 800, and 

 900 tons of high-grade guano. 



When first deposited the guano is wet and sloppy, but under the 

 baking sun this forms a hard thick cake, in color gray, which can be 

 broken with an axe or a pick. As the deposits of later years accu- 

 mulate, the lower layers undergo a change, becoming finely pulver- 

 ized, so that old buried guano can be scooped with a shovel. The 

 old or mineral guano may be of various colors, red, brown, almost 

 black, or light gray, or even green, due in part to chemical changes, 

 in part to foreign substances mixed in. Wlien exposed to the sun, 

 the old guano sometimes acquires a thin crisp whitish crust. Walk- 

 ing over this may give the sound of walking on the icy crust of snow. 

 The old guano does not, however, always bleach white. 



Into the formation of such deposits go not only the excrement but 

 all offal matter, such as waste food, dead bodies of young and old 

 birds, and unhatched eggs — all may be finally blended into one ap- 

 parently undifferentiated mass. 



It is related that one of the islands of the Chincha group was re- 

 duced 100 feet in height by the extraction of the deep crown of guano 

 deposited during past centuries. The story is by no means incredible, 

 since, if the flocks of birds of the South Chincha Island could have re- 

 mained undisturbed and continued breeding in the same place, the 

 top of the island would certainly have been raised a hundred feet in 

 about four centuries. The wonder is not how came the deposits of 

 tens of millions of tons, but what became of the other millions which 

 must have formed during past ages but which are not accoimted for 

 by the records of extraction. How much must have been lost by 

 wasting into the sea! 



There are given below the analyses of several samples of recent guano 

 of guanays from the Baliestas Islands, showing an extremely high 

 value in each case: 



