Seabird guano consists of nitrogen-rich
ammonium nitrate and
phosphates, as well as some earth salts and impurities. (
Ammonium nitrate is a chemical compound, the nitrate salt of the ammonium cation. It has the chemical formula NH4NO3, simplified to N2H4O3. It is a white crystal solid and is highly soluble in water. It is predominantly used in agriculture as a high-nitrogen fertilizer.) Unleached guano from favored locales, such as the
Chincha Islands off the coast of
Peru, typically contains 8 to 16 percent nitrogen (the majority of which is
uric acid), 8 to 12 percent equivalent phosphoric acid, and 2 to 3 percent equivalent
Bat guano is fecal excrement from bats. Commercially harvested bat guano is used as an organic fertilizer.
 All commercially sold bat guano is derived from insect eating bats.
 A study was done that demonstrated that, for fruit bats and insect bats, the composition of their guano was largely the same, and differed mainly based on their diet.