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THE NATIONAL GEOGRAPHIC MAGAZINE 



A GENTLE SLOPE DOTTED WITH THE NESTS OF WHITE-BREAST CORMORANTS: 



CHINCH A ISLANDS 



After the nests had been occupied for three years, an acre of the ground was covered with 

 guano worth $60,000 or more. This rookery comprised about fifteen acres. 



A GUANO-BIRD COLONY OX ONE OF THE BALLESTAS ISLANDS 



The guanays well deserve their name. Their gregarious habits, their choice of level 

 ground and gentle slopes for theii nesting places, and their custom of remaining on land a 

 large part of the time combine to result in the formation of enormous deposits of guano. 



