Thousands of Guanay Cormorant birds fly over and nest on the Ballestas island, south of Lima, October 10, 2011. Ballestas, as with other 21 islands along the Peruvian coast, are home of nearly 4 million migratory birds as guanays, boobies and pelicans which excrement make up the world's finest natural fertilizer. The bird dung, also known as guano, reached its greatest economic importance in the 19th century as a coveted resource, being exported to United States, England and France. Now, Peru hopes to benefit mostly small farmers with an annual production of 20 thousand tons, destined to boost organic agriculture, according to Agrorural, the Rural Agrarian Productive Development Program. Picture taken October 10, 2011. REUTERS/Pilar Olivares
