Tens of thousands of guanay birds fly over their nests on an isolated part of Ballestas island in Peru, Oct. 10, 2011. Along the dry and magnificent Peruvian Pacific coast, 22 scattered islands are home to millions of migratory birds such as guanays, boobies and pelicans..Nesting in these island for millennia their excreta has been used by ancient civilizations to fertilize Andean crops and sustain evolved societies. Now, being one of the finest organic fertilizers in the world they move an economy of around 10 billion dollars, considering the average price of 500 USD a ton, according to Rural Agrarian Productive Development Program (Agrorural) .The bird dung, also known as guano, reached its greatest economic importance in the 19th century as a coveted resource being exported to the United States, England and France..But now the country, being led by a leftist president, hopes to benefit mostly small farmers by boosting organic agriculture through these natural fertilizers.. (Photo Dado Galdieri)