Guano is the accumulated excrement of seabirds, bats, and seals. It is an effective fertilizer due to its high levels of nitrogen, phosphorus, and potassium. Guano has become a valuable commodity in agricultural regions where soil nutrients are scarce. But where is guano actually harvested from?
What is Guano?
Guano refers to the feces and urine of seabirds, bats, and seals that accumulates in certain areas over time. Here are some key facts about guano:
- Guano is high in nitrogen, phosphate, and potassium – key nutrients needed for plant growth.
- Bird and bat guano tends to be higher in nutrients than seal guano.
- Guano deposits accumulate when birds, bats, and seals live and defecate in the same place for long periods.
- Guano deposits can be many meters thick after centuries of accumulation.
- Historically, guano was harvested and exported from islands off the coasts of Peru, Chile, and other countries to fertilize soils in Europe and North America.
The beneficial properties of guano as a fertilizer are what drives its harvest and distribution around the world. Let’s look at where the major guano producing regions are found.
Major Guano Producing Regions
Guano is harvested from coastal islands and cave deposits in several key regions of the world:
Peru and Chile
The coasts of Peru and northern Chile were once the main source of exported guano. Seabird guano was harvested from coastal islands off these countries in the 19th and early 20th centuries. The Chincha Islands off Peru and the Guanape, Macabi, and Lobos de Afuera islands off northern Chile were major guano producing sites. These islands were ideal for guano accumulation due to their lack of predators and stable, dry climates.
Southern Africa
Islands off the southwestern coast of Africa such as Ichaboe Island were also once important sources of guano harvesting. The coastal climate and presence of massive seabird colonies provided ideal conditions for guano buildup. However, overharvesting depleted many of these African guano sites by the mid-20th century.
Australia
Australia is an important modern source of guano harvesting. Islands off the coasts of Western Australia, South Australia, and Queensland provide guano for domestic agricultural use. Some key guano producing islands include Rottnest Island, Kangaroo Island, and Lady Elliot Island which hold large seabird rookeries.
Mexico
Mexico’s Isla Roca Partida in the Gulf of California still produces substantial amounts of guano each year. Major nesting colonies of blue-footed boobies and other seabirds contribute to Mexico’s modern guano harvesting.
Central America and the Caribbean
Smaller scale guano harvesting occurs in island nations throughout Central America and the Caribbean as well. For example, both bat guano and seabird guano are collected from locations in Jamaica and Belize.
United States
In the United States, small quantities of bat guano are mined from caves and abandoned mines in states like Texas, New Mexico, Arizona, and Oklahoma. These operations provide guano for use in organic farming and gardening in North America.
Major Species Contributing to Guano Deposits
The animals that contribute most to harvested guano deposits include:
Seabirds
- Cormorants
- Boobies
- Pelicans
- Gannets
- Penguins
- Albatrosses
- Shearwaters
- Gulls
- Terns
These birds that feed on fish accumulate massive nesting colonies on coastal islands and shore cliffs. Their feces builds up in these breeding sites over the centuries.
Bats
- Fruit bats
- Insect bats
Large bat colonies that roost in caves also contribute guano in many regions. Bats play an especially important role in guano production in more tropical areas.
Seals
Certain seal colonies also produce guano, just in reduced amounts compared to seabird guano. Seal guano results from species like the Cape fur seal, Antarctic fur seal, and Steller sea lion.
How is Guano Actually Collected?
Collecting guano for agricultural use and export is a labor-intensive process. Here are some of the main ways guano is harvested:
- Digging deposits out by hand using shovels and pickaxes.
- Scraping guano off rocks and cliffs near seabird rookeries.
- Breaking up cemented layers and excavating bat guano from cave floors.
- Using heavy machinery and vacuum devices to extract guano.
- Allowing deposited guano to dry and harden before harvesting.
- Transporting guano by conveyor belts or buckets.
- Bagging the final product for ease of distribution.
Strict environmental regulations now limit how and where guano can be collected in many regions. Collectors take only a portion of the annual guano produced at seabird sites. This ensures future deposits are not depleted.
Uses of Guano
The primary use of harvested guano is as an organic fertilizer and soil amendment. Here are some of the specific ways guano is utilized:
- Fertilizer – The high nutrient content of guano makes it an excellent natural fertilizer for agriculture. It slowly releases nitrogen, phosphate, and other nutrients into the soil.
- Soil conditioner – Guano can improve soil texture and water retention when mixed into the soil. This is especially beneficial in sandy soils.
- Compost activator – The microorganisms in guano can help accelerate the composting process when added to compost piles.
- Livestock manure – Bat guano provides nutrients when mixed with manure for use on fields.
- Hydroponics – Dissolving guano in water provides a liquid nutrient source for hydroponic gardening systems.
Demand for guano fertilizer is rising as more farmers shift to organic agriculture and sustainable growing methods.
Environmental Impacts of Guano Harvesting
While guano accumulation itself has little environmental impact, excessive harvesting can damage fragile coastal ecosystems and wildlife habitats. Here are some potential downsides of guano mining:
- Overexploitation can deplete guano reserves and breeding sites for seabirds.
- Disturbance of bird, bat, and seal populations by human activity.
- Physical disruption of island habitats and vegetation.
- Introduction of invasive species to islands by harvesters.
- Soil erosion and landslides resulting from digging activities.
However, small scale and sustainable harvesting practices can prevent long-term ecological damage. Strict regulations now govern the guano industry in many regions including Peru, Chile, and Australia.
History of the Guano Trade
Indigenous Andean people harvested guano for agricultural use for many centuries before the arrival of Europeans. However, large scale guano excavation and export began in the early 1800s. Some key events in the history of the guano trade include:
- 1802 – Alexander von Humboldt first describes high agricultural value of Peruvian guano to Europe.
- 1840s – Guano rush begins as European and North American demand surges.
- 1855 – British government passes protectionist Guano Islands Act to facilitate British annexation of additional guano deposits.
- 1860s – Peak exports of Peruvian guano, mostly to Britain.
- 1879-1884 – War of the Pacific fought between Chile, Peru, and Bolivia over guano resources.
- 1909 – Haber-Bosch process starts providing large scale synthetic fertilizer, reducing guano demand.
At the height of the 19th century guano boom, massive profits were made exporting the fertilizer to European markets. The guano trade brought both economic prosperity and political conflict to Peru and Chile. It prompted new imperial expansion into remote islands containing guano. After synthetic fertilizers emerged in the early 1900s, guano exports steadily declined in scale but continue today.
Modern Guano Market
While much smaller than in the 19th century, a global market for guano still exists today. Some details include:
- Australia, Peru, and Chile remain top exporters of guano.
- Japan, the United States, and Canada are major importing countries.
- Average annual trade is around $10-12 million globally.
- Prices range from $200 to $500 per ton depending on quality.
- Bat guano commands higher prices than seabird guano.
The guano industry now focuses on sustainable harvesting practices. Although synthetic fertilizers dominate global agriculture, guano retains appeal for organic farming. Ongoing scientific research explores enhancing microbe content and nutrient levels to improve guano quality.
Future Outlook
The future direction of the guano industry may shift in several possible directions:
- Guano production may increase if demand grows from organic farmers.
- New high-grade deposits may be developed, especially for bat guano.
- Harvesting innovations could improve efficiency and sustainability.
- Synthetic nitrogen fertilizers remain the mainstream option for most farmers.
- Environmental regulations could further restrict guano mining in sensitive areas.
However, guano harvesting will likely continue on a small scale where it can provide income to coastal communities. The unique value of guano as an organic soil amendment ensures it remains a productive niche in the global fertilizer market.
Conclusion
Although guano was once an infamous commodity that empires battled over, its modern harvest has become more regulated and sustainable. Seabirds, bats, and seals in locations ranging from Peru to Australia all contribute to the world’s supply of guano fertilizer. While guano deposits were once easily depleted, current practices help ensure this unique natural resource is managed properly. The combination of environmental regulations and emerging technologies should allow guano harvesting to continue playing a modest but meaningful role in agriculture.
Guano’s long history and ongoing importance reminds us that even waste products can sometimes become a valuable global commodity when conditions are right. The powerful pull of market forces and agricultural need is capable of transforming feces into literal fool’s gold under the right circumstances.