Guano is accumulated dung or excrement and remains of seabirds, bats and seals found along certain coastal areas and caves. It’s found mainly on the coastal islands of Peru, Africa, Chile and the West Indies. It contains about 6% phosphorus, 9% nitrogen, 2% potassium and moisture. Guano is found mixed with feathers and bones and used mainly as a fertilizer.
Any excrement from birds, seals, or bats, with value to humans as fertilizer, may be referred to as guano. The term originated in Peru, to differentiate useless bird droppings from the nutrient-rich waste of cormorants, pelicans, and other sea birds. The word’s useage has since been widened to include, especially, the mixture of remains and excrement of bats that collect on the floor of caves.
Hundreds of years ago, farmers in South America harvested the white piles of guano from shorelines and islands to use as crop fertilizer. After contact with Europe, the export of guano became economically beneficial for the Colonizers. Bat guano also has a long agricultural and economic history in Cuba. Even today, guano from bat caves in the United States, Asia, Cuba, and South America is marketed as the best organic fertilizer available.