Guano is the accumulated manure of seabirds and bats. It is an extremely effective fertiliser due to its high content of key nutrients essential for plant growth.

When freshly excreted, the guano of insectivorous bats consists of fine particles of insect exoskeleton, which are largely composed of chitin. 

The nutrient profile of guano differs depending on the species and diet of the bats and the age of the guano.