Satellites Reveal Ancient “Mega Traps” Hidden in the Chilean Andes

By A. Merrington, U. of Exeter, Nov. 19, 2025
https://scitechdaily.com/satellites-reveal-ancient-mega-traps-hidden-in-the-chilean-andes/

New satellite analysis reveals a dense concentration of ancient stone hunting traps in Chile’s high Andes, challenging long-held assumptions about early Andean lifeways. (Aerial photo of a double chacu.)
Credit: Dr Adrian Oyaneder

Ancient stone traps in Chile’s highlands show that hunting societies endured alongside early farmers for millennia.

Satellite imagery has uncovered a complex network of large, funnel-shaped hunting traps likely constructed by ancient hunters and herders to capture prey in the high-altitude regions of northern Chile.

The new study of the Andean landscape and its past inhabitants identified 76 stone “chacus,” some stretching for several hundred meters, which were designed to trap vicuñas, wild relatives of the alpaca.

While similar hunting systems have been documented in arid regions such as the Middle East, this discovery marks the first known concentration of such structures in this part of the Andes and suggests they may be older than those associated with the Inkas.

Dr. Adrián Oyaneder, an archaeologist at the University of Exeter, also uncovered signs of settlements and waypoints in the Western Valleys, providing strong evidence that foraging communities persisted there for centuries after agriculture became widespread elsewhere.

A 3D model of a chacu depicting primary (3) and secondary (4) arms, 

and the two-meter drop (2) into the enclosure (1). 

Credit: University of Exeter

The research, conducted as part of Dr. Oyaneder’s doctoral work in Exeter’s Department of Archaeology and History, is published in the journal Antiquity.

Revisiting the mystery of the Western Valleys

“There has long been a discrepancy between what archaeological and ethnohistorical records have told us about life in the Western Valleys of northern Chile during the colonial period,” says Dr Oyaneder. “On the one hand, archaeological research has pointed to a gradual decline in hunting and gathering from 2,000 B.C. onwards with the introduction of domesticated plants and animals. But, historical sources, such as Spanish tax records from the 16th to the 19th centuries, refer to ‘Uru’ or ‘Uro’, which was a generic term for foraging populations who were of little economic interest to the colonizers.”

Using publicly available satellite imagery, Dr. Oyaneder analyzed a 4,600-square-kilometer (about 1,775-square-mile) section of the Camarones River Basin, concentrating on upland regions that had received little prior attention. Over the course of four months, he documented a remarkable number of new archaeological sites.

An illustration of a chacu, courtesy of Gerald Díaz-Vigil. 

Credit: Gerald Díaz-Vigil




Among these were 76 chacus, most of which featured a distinctive V-shaped design composed of two “antennae” built from dry-stone walls approximately 1.5 meters (about 5 feet) tall and averaging 150 meters (around 490 feet) long. These walls converged into an enclosure of about 95 square meters (roughly 1,020 square feet), which was either excavated or built to a depth of roughly two meters (about 6.5 feet)—deep enough to trap animals herded into it by hunters.

Every chacu was situated on a steep, downhill slope, with several incorporating natural terrain features to form one of the antennae. All were positioned at elevations typical of vicuña habitats.

 
A landscape filled with ancient ingenuity

“My reaction when I saw the first chacu was to double and even triple check it,” said Dr Oyaneder. “Initially, I thought it was a bit of a unique occurrence, but as I progressed with my survey, I realized that they were everywhere in the highlands and in a quantity never previously recorded in the Andes.

“And then when I began to read papers and books around the subject, particularly by Thérèse Bouysse-Cassagne and Olivia Harris, there was reference to the choquela, specialized vicuña hunting groups, and words referring specifically to chacu hunting people and chacu hunters.” 

Settlements linked to hunting sites

Dr Oyaneder identified almost 800 small-scale settlements, ranging from single buildings of no more than one square meter to groups of nine or more structures. These were plotted using GIS and grouped into likely clusters linked to nearby chacus and other settlements, all within a 5 km (3 miles) distance.

“The picture that emerges is of a landscape occupied by a range of human groups from at least 6000 B.C. to the 18th century,” adds Dr Oyaneder. “These groups moved strategically across the highlands, tethered primarily to hunting resources, particularly vicuña. The evidence indicates overlapping lifeways, combining hunting-gathering with agropastoral practices, and a network of short-term seasonal settlements and outposts to help people move across rugged and difficult terrain.”

Dr Oyaneder is now conducting further research to date some of these sites and establish whether they represent the first examples of their kind in the Andean region.

 

 

 

 

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