What is guano?

   The guano is a deposit consisting of the accumulated excrement of birds or bats. Bird guano, which forms the vast majority of such deposits, is typically found on islands inhabited by sea-fowl in the rainless areas off the western coasts of South America and Africa, though the de­posits in the former region are now nearly exhausted. Guano is a brown powdery substance from which the soluble constituents may be extracted by rain or sea-water, leading to hardening of the beds. Hence it is divided commercially into 'soluble guano' and 'guano leached." It is a valuable source of artificial manure, by reason of the phosphates it con­tains, and may occur in beds 100 ft. thick. Bat guano is found in caves, as in Kentucky.