The Hadza or Hadzabe people have been hunter gatherers in Tanzania for millennia, and they’re one of the world’s last remaining tribes engaged in this activity, but they’re having to turn to modern technology to protect the shrinking woodland habitat on which they’ve depended for 40,000 years.

They are using carbon trading — a market-based method of regulating greenhouse gas emissions — to save their forests in the Yaeda Valley in Tanzania. The tools of their survival include marking the spot with GPS where trees have been illegally felled.

Carbon trading is the process of buying and selling permits and credits to emit carbon dioxide, according to Fern.org. The world’s biggest carbon trading system is the European Union Emissions Trading System.

The Hadzabe survive by collecting fruit, seeds, honey and roots, and hunting animals, according to Mongabay, an environmental science and conservation website. They live in small camps, moving around the forest depending on the season.

Of all their food staples, honey is the Hadza’s overwhelming favorite, Atlas Obscura reported. By some estimates, the Hadza get 15 percent of their calories from honey.

Beehives are located high in baobabs trees. The Hadza depend on the greater honeyguide, an unassuming black and white bird about the size of a robin, to find honey.

Greater honeyguides, a distinct species of the honeyguide family, love grubs and beeswax, and are great at finding hives.

When the Hadza want honey, they shout and whistle a special tune. You can hear it here on this DW video.

If a honeyguide is around, it’ll fly into the Hadza camp, chattering and fanning out its feathers. The people grab their axes and torches and chase the honeyguide until it lands near a hive. When they pinpoint the correct tree, they smoke out the bees, hack open the hive and harvest the honeycomb from the nest. The honeyguide stays and watches, waiting for leftovers.

Since the 1960s, forests accessible to the Hadzabe have shrunk by 90 percent, threatening the traditional lifestyle of the 1,000 to 1,500 remaining members, Mongabay reported.

A growing number of Datooga people — a farming tribe with cows and goats– have moved into the Yaeda Valley, part of the Great Rift Valley that slices through much of Africa. Their animals overgraze the land leaving little food and water for the herbivores the Hadzabe hunt. Another tribe, the Sukuma, cut down trees to build farms in the area.

It is now illegal to cut down trees in land traditionally used by the Hadzabe in Yaeda Valley, DW reported.

Hadzabe patrol the protected forests and report any deforestation, poaching or new settlements to local authorities. Their salary is paid by Carbon Tanzania from revenue made from carbon sales.

In 2007, the threats to the Hadzabe and Yaeda Valley got the attention of conservationists Marc Baker and Jo Anderson. In 2010, Baker and Anderson co-founded Carbon Tanzania, a social enterprise to help the Hadzabe benefit from reducing emissions from deforestation and forest degradation. A market-based acronym now exists for the term — it’s called REDD carbon trading, according to Mongabay:

“The main threats to this landscape – and this is pretty typical across Tanzania – are economic migrants,” said Baker in an interview with Mongabay. “People moving, because the landscapes in which they have lived unsustainably for many years are collapsing.”

Ground surveys and satellite imagery suggested the Yaeda Valley was losing 191 hectares or 0.93 percent of forest every year.

“At the time, the mechanism for REDD (reducing emissions from deforestation and forest degradation) was developing in an academic sense, and we recognized this model immediately,” explained Baker. “You could reduce deforestation by creating a steady flow of revenue based on land-use planning and participatory forest management.”

In 2011, the Hadzabe signed a 20-year contract with Carbon Tanzania to sell forest carbon offsets on their behalf. Before trading could begin, the amount of carbon stored in the Yaeda Valley had to be counted. Hadzabe members and Carbon Tanzania measured the area’s carbon reserves through above-ground biomass surveys and Landsat and Google Earth satellite images.

They found that each hectare (about 2.5 acres) of  acacia woodland stored about 116 metric tons of carbon dioxide. That’s the equivalent of greenhouse gas emissions from 25 passenger cars driven for a year.

Carbon Tanzania registered the project with Plan Vivo Foundation, an organization that certifies fairly traded carbon initiatives.

Baker and Anderson monetized the carbon saving produced by the project. They approached local and international companies that wanted to to reduce their carbon footprint and began selling carbon offsets.

Carbon Tanzania’s Yaeda Valley project covers almost 80,000 acres of forest and counts 16,011 tons of sequestered carbon annually—the equivalent of taking 3,300 passenger cars off the road for a year.

Revenue from their sales protects the forests. Carbon Tanzania pays Hadzabe villagers a monthly salary to patrol the forests and make sure there have been no trees felled or new settlements.

Scouts make $23 a month which they usually spend on food like maize to supplement their diet and clothes.

In addition operating costs, 60 percent of the revenue from the carbon offset sales is paid directly to the community — $150,000 has been paid so far to the villages of Domanga and Mongo wa Mono in the Yaeda Valley. Every six months, the entire community meets to decide how to spend the money.

Anthropologists have been studying the Hadza for centuries, Atlas Obscura reported. The Hadza have “a food-based method of self-understanding: they describe their predecessors based on what, and how, they ate,” the report said.

Today’s Hadza people have several meal strategies. Their hunting and gathering grounds are being replaced by maize farms, private game reserves and livestock. Some work jobs and buy food, but 200-to-300 of the 1300-or-so Hadza still left survive almost entirely on wild foods — tubers, meat, fruit, and honey.