NO. 2298. THE GUANO BIRDS OF PERU—COKER. 475 



the "Isla de Sur/' "Isla del Media," and "Isla del Norte." These 

 islands are about 11 nautical miles from the port of Pisco, or about 

 4 and 9 miles, respectively, from the point of Paracas Peninsula. 

 Tliey are the most famous in the history of the guano industry; 

 sm.all as they are, and without a single permanent human habitation, 

 the name of Chinchas is known to every seaport in the world. ^ 

 Between 1850 and 1872 nearly 11,000,000 tons of guano are said to 

 have been exported from these islands alone, and almost the entire 

 deposit appears to have been of very high quality, with 13-14 per 

 cent of nitrogen and about an equal proportion of phosphoric anhy- 

 dride. The value of such a deposit at ordinary prices would be 

 nearly three-quarters of a billion dollars, but the area of all the 

 islands if combined into one would not be greater than that of a 

 small-sized farm. 



When the Ballestas were visited in May, 1907, each of the three 

 islands had large flocks of cormorants, all of which, however, had 

 been disturbed by the opening of the season for the extraction of 

 guano. The smallest of the three flocks had occupied the southwest 

 corner of the north island, beyond the bluff and on comparatively 

 level ground. The main part of the rookery was bounded by nearly 

 straight lines, being 85 meters in length, with an average width of 

 54 meters. The area was, therefore, approximately 4,600 square 

 meters. 



The south island of this group is some 300 feet in height and diffi- 

 cult of ascent. Its small top was nearly half covered with a compact 

 rookery of between 10 and 12 thousand square meters. The area 

 of the breeding ground on the middle island was only sUghtly less. 

 In all, about 150,000 birds had nested at these islands during the 

 preceding summer, for it was found that we could safely estimate 

 the flock at about six breeding birds to the square meter. 



At the Chincha Islands, visited in June, 1907, the guanays were 

 using only the south island. But here was a rookery which for its 

 size and compactness can scarcely be rivaled in any part of the 

 world (pis. 61 and 62). Sixty thousand square meters of ground, 

 or 15 acres, were closely covered with cormorant nests. It occupied 

 about two-thirds of the surface of the island, embracing the crown 

 and the gentle slopes of the hill surmounting the island. The nests 

 were very uniformly spaced, about three to the square meter, and 

 not an available meter of ground within the outside limits of the 

 rookery was unoccupied. In one place 39 nests were counted in 12 

 square meters; in another, 52 nests in 18 square meters; in a third 

 place, 33 nests to 9 square meters. These places were not more 

 crowded than any other points within the limit of the rookery, the 



' No less than 346 vessels are said to have embarked guano at the Chinchas Islands in 1858 

 <p.205 of "Derrotero," previously cited, p. 453.) 



