Guano (via Spanish, ultimately from the Quechua wanu) is the excrement of seabirds, cave-dwelling bats, pinnipeds, or (in English usage) birds more generally. As a manure, guano is a highly effective fertilizer due to its exceptionally high content of nitrogen, phosphate, and potassium, three nutrients essential for plant growth. The nineteenth-century guano trade played a pivotal role in the development of modern input-intensive farming practices and inspired the formal colonization of remote bird islands in many parts of the world. During the twentieth century, guano-producing birds became an important target of conservation programs and influenced the development of environmental consciousness. Today, guano is increasingly sought after by organic farmers.