FISHERIES AND GUANO INDUSTRY OF PERU. 359 
It may be of interest here to consider for a moment the potential commercial 
value of such flocks of birds. Let us assume that each of these birds leaves upon 
the island daily a single ounce of guano. This is actually an underestimate, as 
such a rate of deposition would not account for the quantity of guano actually 
extracted after a year’s accumulation on a rookery; but on this assumption 
of 1 ounce a day for each bird, the deposit would grow daily by 1,000,000 ounces, 
62,500 pounds, or 28 long tons. A million birds would then produce over 
10,000 long tons of guano per year. Such an amount is probably not actually 
formed at this ground, for the reason that a million birds is a decided overestimate 
of the average number of birds on the rookery throughout the year. However,on 
the assumption of 1 ounce of guano per day per bird, it follows that 100 birds 
would produce 1 long ton of guano per year. 
We may come more nearly to the actual conditions. From the various 
calculations I have made it appears that a rookery will yield about 1 long ton 
of guano per year for 28 nests. This guano of the ‘‘guanayes” is very high in 
nitrogen, giving an analysis of 12 to 14 per cent and higher, and we may value 
it at $40 per ton.” Twenty-eight nests, or 28 pairs of birds, have an annual 
producing value of $40. We give a fair idea of the commercial significance of 
these birds to Peru when we say that each brace of birds contributes annually 
$1.43 worth of guano, besides leaving a pair of offspring to continue its service. 
Is it not, then, of the greatest importance that the fullest protection should be 
extended the birds, and every possible precaution taken to insure that there may 
be the maximum number of birds at every rookery, and that these birds may 
remain ypon the rookery the maximum amount of time? 
Previous to making the above computation, from observations at other 
rookeries, I had estimated the number of nests on the south island of the Chin- 
chas at 180,000, and, by an independent series of measurements of the deposits of 
guano at various places in the rookery after two years of accumulation, had esti- 
mated the amount of guano at between 12,000 and 15,000 tons. Making a new 
calculation on the basis of the figures just worked out—that is, 1 ton to 28 nests— 
the 180,000 nests would give 6,400 tons per year, which is in close agreement with 
the original computation from measures and weights taken on the rookery. 
4 The cost of guano to a Peruvian farmer can not be taken asa basis of valuation, since the govern- 
ment practically gives the guano to him, exacting a tax of only 1 sol (about 49 cents) the ton. The 
expense to the farmer is merely the cost of extraction and transportation. The cost of a ton of 9 per 
cent guano on the farm is, therefore, only $12 or $13 in American gold. This cost, however, does 
not at all represent the value of the guano, if the cost were based on the ordinary laws of supply and 
demand. ‘The real value to the farmer can not be computed. 
The guano for export was consigned to the exporting company many years ago by a process of 
adjustment, in return for the acceptance of certain obligations; so that it is not practicable, either, to 
calculate the value of the export guano on the ground. 
However, considering the high selling value of guano of such excellent quality in foreign markets, 
and since the cost of extraction is less than $5, and the freight relatively low, it can not be considered 
unreasonable to assume that guano of this high anaylsis has a value to the world ofa$4o per ton. 
