VALUE OF BIRDS TO MAN. 83 
tudes of the Pacific, near the equator, guano once accumulated 
in tremendous deposits. It dried quickly, and where there 
were no rains to wash it away it was preserved with most of its- 
fertilizing constituents intact. The guano found on islands 
outside the dry latitudes is of less value, as its nitrogen is 
quickly washed out or dissipated. The importance of guano 
as a fertilizer was recognized in Peru by the Indians more 
than three centuries ago. Under the Incas the birds on the 
Chincha Islands were carefully protected, and the deposits 
of guano jealously guarded. It is said that the penalty of 
death was inflicted on any one who killed birds near these 
rocks in the breeding season. 
Humboldt, returning from his travels in tropical America 
in 1804, carried some samples of guano to Europe, and first 
called attention to the value of the deposits of this substance 
on the Chincha Islands; but it was nearly forty years later 
that guano became a stimulus to intensive agriculture, and 
furnished a source of revenue to civilized nations. The vast 
deposits on these three islands covered the rocks in some 
places to a depth of ninety or one hundred feet. The amount 
still undisturbed in 1853 was estimated by the official sur- 
veyors of the Peruvian government as twelve million, three 
hundred and seventy-six thousand, one hundred tons. Its 
use was first attempted in England in 1840; at that time the 
beds seemed inexhaustible. The guano trade soon became 
so important as to be a source of diplomatic correspondence 
between nations. It is said to have brought Peru and Chile 
to the verge of war. By 1850 the price of Peruvian guano 
had advanced in the United States to fifty dollars a ton, and 
American enterprise began to seek guano elsewhere. 
. Americans have since filed with the government claims 
to about seventy-five guano islands in the South Pacific or 
in the Caribbean Sea. The vast deposits on the Chinchas 
are nearly exhausted, and fertilizers are now manufactured to 
supply the demand. Undoubtedly, however, the discovery 
and use of guano marked the beginning of the present enor- 
mous trade in commercial fertilizers. The manurial value 
of the phosphoric acid and nitrogen contained in fish has 
now become quite generally recognized, and fleets of small 
