How to Harvest Guano

Find an optimal location. (Peru is known for its guano production, because it has plenty of fish-eating birds and insect-eating bats to produce it, and the dry weather keeps the nitrates intact; rain would wash them out.) Many island nations have large guano deposits.

Research government restrictions, such as permission requirements and time limitations, for the chosen area. (For example, in Peru, people cannot harvest guano from large penguin colonies.) Some islands restrict harvesting to non-breeding seasons so that birds will not be disturbed.

Find guano at ideal times. For example, bat guano builds up on the bottom of caves and should be harvested at night when the bats are out. Bird guano is found on rocky coasts and should be harvested during the day, during periods when the birds are not breeding or rearing chicks.

Excavate with a shovel or pickax, starting with the first layer and taking care not to harvest any organic matter with it. The easy-to-excavate first layer is made of fresher, softer excrement. The second layer is older, but no less valuable. The bottom layer, however, which has microorganisms eating the nutrients, is less valuable.

Collect the guano in large bags and transport.

Analyze and process the guano. Analyze the easier-to-handle bat guano and prepare it for sale. Bird guano, however, is harder; it must be pulverized before it can be prepared as a marketable product.