Most commercially sold bat guano is derived from insect eating bats. Harvesting from large roosts with millions of bats is sustainable. The caves where these roosts are found must be fenced and guarded to prevent the caves from being used as rubbish dumps. Insect eating bat guano has an average NPK of 7-3-1. Bat populations in protected caves increase yearly until the roosting area is full.
Most species of fruit bats roost in small colonies in crevices, ledges, trees, and other natural settings. Commercial harvesting is impossible due to small colony size. The raw guano is extremely sticky, and the smell unbearable. The average NPK of fruit bat guano is 3-1-6. Habitat loss is a threat to the survival of many species of fruit, pollen, and nectar eating bats.
This guano is derived from marine bird excrement. The phosphate is derived from fish bones digested by seabirds, and hardened over millennia into rock. This rock is collected from ridges, cliffs and mines, then crushed, sieved, and sterilized in a quarantined factory in Indonesia before packaging for export.