Bird guano is the accumulated excrement and remains of birds such as cormorants, pelicans, and gannets.
Guano is 11 to 16 percent nitrogen, 8 to 12 percent phosphoric acid, and 2 to 3 percent potash.
The excellent fertilizer is harvested from islands off Peru, Baja California, and Africa.
Bat and seal guano is also highly prized.