Guanos are natural fertilizers formed by the accumulation of bird, bat, and seal excreta in soils and rocky coastal areas. While the term "guanos" is already considered a synonym for bird droppings, guano actually refers to any organic material rich in nitrogen, phosphorus, and potassium. Other synonyms for guano include animal excrement, manure, compost, organic matter, and soil amendments. These terms are often used interchangeably in the agricultural and gardening industries as they all serve the purpose of enhancing soil fertility and promoting plant growth. Knowing the different synonyms for guanos helps gardeners and farmers choose the right type of fertilizer for their crops, depending on their nutrient needs and availability.