Bird guano created wealth for ancient Peruvian community
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- The Chincha kingdom in southern Peru, which existed 1,000 years ago, prospered because farmers used bird guano as fertilizer to grow high maize (corn) yields.
- Scientists found high nitrogen levels in ancient maize, showing guano from the nearby Chincha Islands boosted crop production.
- Increased food production created wealth, as well as strengthened trade and political power, helping the Chincha form alliances with the Inca Empire.
Bird guano boosted agricultural yields for Chincha kingdom
The Chincha kingdom was an ancient community that flourished in southern Peru from 900 CE to 1,450 CE (1,126 to 576 years ago). They were wealthy largely because farmers produced high maize (corn) yields, a primary food staple. On February 12, 2026, scientists at the University of Sydney said Chincha kingdom farmers were able to get those high yields because they used bird guano (accumulated bird droppings) as fertilizer. The researchers discovered this when they ran chemical analyses on maize from ancient tombs, where they found high levels of nitrogen that could only have come from the guano.
Jacob Bongers, of the University of Sydney, is the lead author of the study. He said:
Seabird guano may seem trivial, yet our study suggests this potent resource could have significantly contributed to sociopolitical and economic change in the Peruvian Andes.
Guano dramatically boosted the production of maize (corn), and this agricultural surplus crucially helped fuel the Chincha kingdom’s economy, driving their trade, wealth, population growth and regional influence, and shaped their strategic alliance with the Inca Empire.
In ancient Andean cultures, fertilizer was power.
The scientists published their study in the peer-reviewed journal PLOS One on February 11, 2026.
An ancient community of farmers and seafarers
The Chincha Valley, on the Pacific coast of Peru, was once home to about 100,000 people. Even though that region was largely arid, agriculture was possible because the Chincha River, originating from the Andes, flowed through the valley.
By the 11th century, the Chincha kingdom had developed agricultural systems, including irrigation and field fertilization with bird guano. In addition, they were also a seafaring people who built large rafts with sails that carried cargo and people.
In 1534, Spanish conquerors came to Chincha Valley. Then, not long after, the Chincha population steeply declined over several decades, their demise mostly due to political turmoil and new diseases brought by the Spanish.
Uncovering the connection between agriculture and bird guano
The scientists studied the biochemical signatures in 35 samples of maize, found in burial tombs in the Chincha Valley. As a result, they found very high levels of nitrogen in the maize, far more than was naturally available in the soil.
Indeed, this finding proved that ancient Chincha Valley farmers fertilized their maize using seabird guano. That’s because guano is quite high in nitrogen, due to the seabirds’ fish diet.
Bongers said:
The guano was most likely harvested from the nearby Chincha Islands, renowned for their abundant and high-quality guano deposits. Colonial era writings we studied report that communities across coastal Peru and northern Chile sailed to several nearby islands on rafts to collect seabird droppings for fertilization.
Emily Milton of the Smithsonian Institution, a paper co-author, added:
The historical records documenting how bird guano was applied to maize fields helped us interpret the chemical data and understand the regional importance of this practice.
Our work extends the known geographic extent of guano fertilization, echoing recent findings in northern Chile, and suggests soil management began at least around 800 years ago in Peru.
Bird guano created power in an inhospitable region
Farming was not easy along the coast of Peru. That’s because conditions are very dry and irrigated soil can quickly lose nutrients. However, in the Chincha Valley, the irrigation system and fertilizing with guano enabled farmers to grow crops, especially their staple food, maize. Consequently, the ripple effect of an abundant maize supply supported other endeavors, such as trade and fishing.
Bongers commented:
We know the Chincha were extraordinarily wealthy and one of the most powerful coastal societies of their time. But what underpinned that prosperity? Previous research often pointed to spondylus shells, the spiny oyster, as the key driver of merchant wealth.
Our evidence suggests guano was central to the Chincha kingdom’s success, with the Chincha’s maritime knowledge and access to the Chincha Islands likely reframing their strategic importance in the region.
Incas prized maize from the Chincha Valley
The Inca Empire, a highly developed civilization in the Andes Mountains, valued maize. They used it to make a ceremonial beer called chicha. However, they could not grow maize at their high altitude.
Bongers said:
Guano was a highly sought-after resource the Incas would have wanted access to, playing an important role in the diplomatic arrangements between the Inca and the Chincha communities.
It expanded Chincha’s agricultural productivity and mercantile influence, leading to exchanges of resources and power.
Later, around 1480, the Chincha kingdom became part of the Inca Empire.
Archaeological artifacts reflect Chincha Valley culture
The artwork of the Chincha people reflected strong ties to their livelihoods. For instance, pottery, ceramics and textiles featured sprouting maize, fish and seabirds.
Bongers observed:
Together, the chemical and material evidence we studied confirms earlier scholarship showing that guano was deliberately collected and used as a fertilizer.
But it also points to a deeper cultural significance, suggesting people recognized the exceptional power of this fertilizer and actively celebrated, protected and even ritualized the vital relationship between seabirds and agriculture.
Co-author Jo Osborn of Texas A&M University added:
The true power of the Chincha wasn’t just access to a resource; it was their mastery of a complex ecological system. They possessed the traditional knowledge to see the connection between marine and terrestrial life, and they turned that knowledge into the agricultural surplus that built their kingdom. Their art celebrates this connection, showing us that their power was rooted in ecological wisdom, not just gold or silver.
Bottom line: The ancient Chincha kingdom of Peru prospered thanks to high maize yields, made possible by bird guano from nearby islands.
Source: Seabirds shaped the expansion of pre-Inca society in Peru
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