Guano (from Quechua wanu via Spanish) is the accumulated excrement of
seabirds and bats. As a manure, guano is a highly effective fertilizer
due to its exceptionally high content of nitrogen, phosphate and
potassium: nutrients essential for plant growth. The 19th-century
guano trade played a pivotal role in the development of modern
input-intensive farming practices and inspired the formal human
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.
5 In popular culture
6 See also
8 Further reading
9 External links
Seabird guano consists of nitrogen-rich ammonium nitrate and urate,
phosphates, as well as some earth salts and impurities. (Ammonium
nitrate is a chemical compound, the nitrate salt of the ammonium
cation. It has the chemical formula NH4NO3, simplified to N2H4O3. It
is a white crystal solid and is highly soluble in water. It is
predominantly used in agriculture as a high-nitrogen fertilizer.)
Bat guano is fecal excrement from bats. Commercially harvested bat
guano is used as an organic fertilizer. All commercially sold
bat guano is derived from insect eating bats. A study was done that
demonstrated that, for fruit bats and insect bats, the composition of
their guano was largely the same, and differed mainly based on their
Chincha Islands where guano was found in abundance. Mining was done on
site and ships transported it to Europe
Mining guano in the
Chincha Islands off the central coast of Peru
Advertisement for guano, 1884.
The word "guano" originates from the Andean indigenous language
Quechua, which refers to any form of dung used as an agricultural
fertilizer. Archaeological evidence suggests that Andean people have
collected guano from small islands and points located off the desert
Peru for use as a soil amendment for well over 1,500 years.
Spanish colonial documents suggest that the rulers of the Inca Empire
assigned great value to guano, restricted access to it, and punished
any disturbance of the birds with death. The
Guanay cormorant has
historically been the most abundant and important producer of guano.
Other important guano producing species off the coast of
Peru are the
Peruvian pelican and the Peruvian booby.
In November 1802,
Alexander von Humboldt
Alexander von Humboldt was the first European to
encounter guano and began investigating its fertilizing properties at
Callao in Peru, and his subsequent writings on this topic made the
subject well known in Europe. During the guano boom of the nineteenth
century, the vast majority of seabird guano was harvested from
Peruvian guano islands, but large quantities were also exported from
the Caribbean, atolls in the Central Pacific, and islands off the
coast of Namibia, Oman, Patagonia, and Baja California. At that time,
massive deposits of guano existed on some islands, in some cases more
than 50 m deep. In this context the United States passed the Guano
Islands Act in 1856, which gave U.S. citizens discovering a source of
guano on an unclaimed island exclusive rights to the deposits. Nine of
these islands are still officially U.S. territories. Control over
guano played a central role in the
Chincha Islands War (1864–1866)
between Spain and a Peruvian-Chilean alliance. Indentured workers from
China played an important role in guano harvest. The first group of 79
Chinese workers arrived in
Peru in 1849; by the time that trade ended
a quarter of a century later, over 100,000 of their fellow countrymen
had been imported. There is no documentary evidence that enslaved
Pacific Islanders participated in guano mining. Between 1847 and
1873, there was a significant increase in Peruvian guano exports, and
the revenue from this momentarily ended the fiscal necessity of the
colonial head tax.
After 1870, the use of Peruvian guano as a fertilizer was eclipsed by
saltpeter in the form of caliche extraction from the interior of the
Atacama Desert, not far from the guano areas. During the War of the
Pacific (1879–1883) Chile seized much of the guano as well as Peru's
nitrate-producing area, enabling its national treasury to grow by 900%
between 1879 and 1902 thanks to taxes coming from the newly acquired
lands. Contrary to popular belief, seabird guano does not have
high concentrations of nitrates, and was never important to the
production of explosives; bat and cave-bird deposits have been
processed to produce gunpowder, however. High-grade rock phosphate
deposits on Nauru, Banaba Island,
Christmas Island (Indian Ocean) and
other raised atolls, long supposed to derive from bird guano, have
more recently been considered the result of marine
Since 1909, when the Peruvian government took over guano extraction
for use by
Peru farmers, the industry has relied on production by
living populations of marine birds. U.S. ornithologists Robert Cushman
William Vogt promoted the Peruvian industry internationally
as a supreme example of wildlife conservation, while also drawing
attention to its vulnerability to the
El Niño phenomenon. South
Africa independently developed its own guano industry based on
sustained-yield production from marine birds during this period, as
well. Both industries eventually collapsed due to pressure from
overfishing. The importance of guano deposits to agriculture
elsewhere in the world faded after 1909 when
Fritz Haber developed the
Haber-Bosch process of industrial nitrogen fixation, which today
generates the ammonia-based fertilizer responsible for sustaining an
estimated one-third of the Earth's population.
DNA testing has suggested that new potato varieties imported alongside
Peruvian seabird guano in 1842 brought a virulent strain of potato
blight that began the Irish Potato Famine.
A herring gull (Larus argentatus) excreting waste near
The ideal type of guano is found in exceptionally dry climates, as
rainwater volatilizes and leaches nitrogen-containing ammonia from
guano. In order to support large colonies of marine birds and the fish
they feed on, these islands must be adjacent to regions of intense
marine upwelling, such as those along the eastern boundaries of the
Pacific and South Atlantic Oceans.
Post-depositional decomposition and ammonia volatilization of penguin
guano also plays an important role in the evolution of ornithogenic
sediments in the cold and arid environment of Antarctica (McMurdo
Sound of the
Ross Sea region, East Antarctica).
In agriculture and gardening guano has a number of uses, including as:
soil builder, lawn treatments, fungicide (when fed to plants through
the leaves), nematicide (decomposing microbes help control nematodes),
and as composting activator (nutrients and microbes speed up
In popular culture
In his poem 'Guanosong',
Joseph Victor von Scheffel
Joseph Victor von Scheffel described the
development of the manure in humouristic verses in the middle of the
19th century. He used poetry for a version of the then-popular polemic
against Hegel's Naturphilosophie. The poem starts with highly
sophisticated wording and allegations to Heinrich Heines
may be sung along the same tunes, as from 1837 by Friedrich
Silcher. The poem ends however with the grunt statement of a
Swabian rapeseed farmer from Böblingen, which praises the seagulls,
providing better 'birdshit' even than fellow countryman Hegel. It has
been translated by, among others, Charles Godfrey Leland.
Bat Cave mine
Guano Era, Peru
Guano Islands Act
^ a b c Cushman, Gregory T. (2013).
Guano and the Opening of the
Pacific World: A Global Ecological History. Cambridge and New York:
Cambridge Univ. Press. ISBN 9781107004139.
^ Oregon Department of Agrigulture "Oregon Department of Agrigulture:
Guano Definition", AAPFCO Website (Association of American Plant
Food Control Officials), USA, 31 March 2016. Retrieved on 12 December
^ California Department of Food and
Agriculture "California Department
of Food and Agriculture-Notice to Fertilizing Material Licensees-Use
of the term “
Bat Guano” on Fertilizing Material Labels", Email to
membership, USA, 11 May 2017. Retrieved on 12 December 2017.
Guano "Insect Eating (Insectivorous)
Bat Guano", RealGuano
Website, USA, 21 September 2017. Retrieved on 12 December 2017.
^ Emerson, Justin K.; Roark, Allison M. (2007). "Composition of guano
produced by frugivorous, sanguivorous, and insectivorous bats". Acta
Chiropterologica. 9: 261–267.
^ Szpak, Paul; Millaire, Jean-Francois; White, Christine D.;
Longstaffe, Fred J. (2012). "Influence of seabird guano and camelid
dung fertilization on the nitrogen isotopic composition of field-grown
maize (Zea mays)". Journal of Archaeological Science. 39 (12):
^ a b Hutchinson, G. Evelyn (1950). "Survey of Existing Knowledge of
Biogeochemistry: 3. The Biogeochemistry of Vertebrate Excretion".
Bulletin of the American Museum of Natural History. 96: 1–554.
^ Skaggs, Jimmy (1994). The Great
Guano Rush: Entrepreneurs and
American Overseas Expansion. New York: St. Martin's.
^ Méndez, Cecilia (1987). Los trabajadores guaneros del Perú,
1840–1879. Lima: Universidad Nacional Mayor de San Marcos.
^ Larson, Brooke (2004). Trials of Nation Making: Liberalism, Race,
and Ethnicity in the Andes, 1810-1910. Cambridge: Cambridge University
Press. p. 146. ISBN 978-0521567305.
^ Crow, The Epic of Latin America, p. 180
^ McKelvey VE (1967). "A summary of the salient features of the
geology of phosphate deposits, their origin, and distribution" (PDF).
Geological Survey Bulletin. 1252-D. D14.
^ Bernat M, Loubet M, Baumer A (1991). "Sur l'origine des phosphates
de l'atoll corallien de Nauru" [On the origin of phosphates from the
Nauru atoll] (PDF). Oceanologica Acta (in French). 14 (4). CS1
maint: Uses authors parameter (link)
^ Glenn, Craig, et al., eds. (2000). Marine Authigenesis: From Global
to Microbial. Tulsa, OK. CS1 maint: Extra text: authors list
^ Wolfe, David W. (2001). Tales from the underground a natural history
of subterranean life. Cambridge, Mass: Perseus Pub.
ISBN 0-7382-0128-6. OCLC 46984480.
^ Dwyer, Jim (10 June 2001). "June 3–9; The Root of a Famine". The
New York Times. p. 2.
^ Gómez-Alpizar, Luis; et al. (2007). "An Andean origin of
Phytophthora infestans inferred from mitochondrial and nuclear gene
genealogies". PNAS. 104: 3306–11. doi:10.1073/pnas.0611479104.
PMC 1805513 . PMID 17360643.
^ Nie, Yaguang; Liu, Xiaodong; Wen, Tao; Sun, Liguang; Emslie, Steven
D. (2014). "Environmental implication of nitrogen isotopic composition
in ornithogenic sediments from the
Ross Sea region, East Antarctica:
Δ15N as a new proxy for avian influence". Chemical Geology. 363:
^ "h2g2 - Seabird
Bat Dung". Bbc.co.uk. Retrieved
^ Note: A scan of the Loreley sheet music and lyrics (printed in 1859;
note the spelling "Lorelei") are available on the commons in three
images: File:Lorelei1.gif, File:Lorelei2.gif, File:Lorelei3.gif
^ Charles Godfrey Leland, Gaudeamus! Humorous Poems by Joseph Viktor
von Scheffel, Ebook-Nr. 35848 on gutenberg.org
Guano and the Opening of the Pacific World: A Global Ecological
History, Gregory T. CushmanCambridge University Press, 25.03.2013, p.
Cushman, Gregory T. (2013).
Guano and the opening of the Pacific
world: a global ecological history. Cambridge; New York: Cambridge
University Press. ISBN 9781107314030. Retrieved 2013-06-13.
Hague, James D. (1862). On the phosphatic guano islands of the Pacific
Ocean. Retrieved 2013-06-13.
Skaggs, Jimmy M. (1994). The great guano rush: entrepreneurs and
American overseas expansion. New York: St. Martin's Press.
Robinson, Solon (1853). Guano: a treatise of practical information for
farmers. New York: Solon Robinson.
Guano Company (1876). The Pacific
Guano Company; its history;
its products and trade; its relation to agriculture. Exhausted guano
islands of the Pacific Ocean; Howland's island, Chiacha Islands, etc.,
etc. The Swan Islands. The marl beds and phosphate rock of South
Carolina. Chisolm's Island phosphate. The menhaden. Cambridge: Printed
for the Pacific
Guano Company at the Riverside Press.
Teschemacher, James E. (1845). Essay on guano; describing its
properties and the best methods of its application in agriculture and
horticulture; with the value of importations from different
localities; founded on actual analyses, and on personal experiments
upon numerous kinds of trees, vegetables, flowers, and insects, in
this climate. Boston: A.D. Phelps.
Eden, Thomas Edward (1846). The search for nitre, and the true nature
of guano: being an account of a voyage to the south-west coast of
Africa: also a description of the minerals found there, and of the
guano islands in that part of the world. London: R. Groombridge.
Morrell, Benjamin (1832). A Narrative of Four Voyages...etc. New York:
J & J Harper. Retrieved December 17, 2009.
Teale, E.O. (1934). The Limestone caves and hot springs of the Songwe
river (Mbeya) area with the notes associated
Guano deposits. XII. The
East Africa Natural History Society.
Pissis, Aimé (1878). Nitrate and
Guano Deposits in the Desert of
Atacama: An Account of the Measures Taken by the Government of Chile
to Facilitate the Development Thereof. London: Taylor and
Duffield, Alexander James (1877).
Peru in the guano age: being a short
account of a recent visit to the guano deposits, with some reflections
on the money that they have produced and the uses to which it has been
applied. London: Richard Bentley and Son.
Duffield, Alexander James (1881). The Prospects of Peru: The End of
Guano Age and a Description Thereof. With Some Account of the
Guano Deposits and Nitrate Plains. London: Newman & Co.
Hollett, Davi (2008). More Precious than Gold: The Story of the
Guano Trade. Fairleigh Dickinson. ISBN 1611473578.
Nesbit, John Colis (1856). On agricultural chemistry, and the nature
and properties of Peruvian guano. London: Longman and Co.
"Prospectus of the American
Guano Company". 1855. Retrieved
Coker, Robert Ervin (1910). The fisheries and the guano industry of
Peru. Washington DC: Government Printing Office. Retrieved
"Report of the Inspector of Guano : Maryland". 1849. Retrieved
United States Department of Agriculture, Office of Experiments (1918).
Bat guanos of Porto Rico and their fertilizing value. Mayagüez, P.R.:
Porto Rico Agricultural Experiment Station.
Wikimedia Commons has media related to Guano.
Guano and Cave Preservation
The dictionary definition of guano at Wiktionary
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