The corridor was conceived inside Brazil's Ministry of the Environment under the Ecological Corridors Project, finalized in December 2000. A grant agreement with the World Bank followed in December 2001, and the project went operational in March 2002. Planners faced a choice: where to start? Brazil's two most biodiverse biomes are the Amazon and the Atlantic Forest, and each needs different tools - the Amazon still exists as a mostly continuous forest, while the Atlantic Forest exists as islands. Priority went to two pilot corridors, one in each biome: the Central Amazon Ecological Corridor and this one. The idea was to test connectivity strategies under very different conditions, learn what worked, and apply the lessons to future corridors. In the central Atlantic Forest the job is managed by state committees of the Atlantic Forest Biosphere Reserve, a structure that puts traditional communities, environmental NGOs, producers, and all three levels of government at the same table.

The corridor's most striking feature is how little of it the state actually owns. By 2015 it encompassed roughly 21.5 million hectares across 163 municipalities, stretching about 1,200 kilometers north to south and including patches of ocean out to the continental shelf. Inside those borders, 128 formal conservation units total around 2.2 million hectares - Bahia contributes 10 federal, 15 state, 7 municipal, and 28 private reserves; Espírito Santo adds 21 federal, 17 state, 17 municipal, and 41 private. About 95 percent of the corridor's land is privately owned. This means the corridor works only if landowners work with it. Incentive programs pay farmers to retain forest on their property, private natural heritage reserves (RPPNs) create legal protection for forest on working farms, and sustainable production practices such as shade-grown cacao and agroforestry offer livelihoods that let the forest stand. The strategy acknowledges a blunt fact: in a country where the state cannot afford to buy the forest it needs to protect, conservation has to be made profitable.

The species list the corridor protects reads like a summary of why the Atlantic Forest matters. The golden lion tamarin - a small primate with a mane of deep orange fur - is found nowhere else on Earth; it was brought back from near-extinction by captive breeding in the 1980s, and survives now in reforested corridors like this one. The bristle-spined rat (Chaetomys subspinosus), a shy nocturnal rodent with quills like a porcupine's, is another Atlantic Forest endemic. Three-toed sloths move through the canopy in a pace that makes tamarins look frantic. Add several thousand endemic plant species, hundreds of bird species, and the usual suspects of tropical rainforest - tapirs, ocelots, howler monkeys, snakes you would not want to meet - and the biological value of the corridor is hard to overstate. Southern Bahia is one of the two centers of endemism within the corridor, home to that extraordinary figure of 458 tree species in a single hectare, more than all but a handful of places on the planet.

The work of the corridor is less about creating new protected areas than about making the existing ones connected. Strips of forest along streams, reforested pasture, agroforestry plots around villages, and recovering secondary forest all add up into pathways that let a tamarin troop or a sloth family move between patches that would otherwise be too small to sustain them. Restinga forests on sandy coastal soils, mangroves along river estuaries, and semi-deciduous inland forests are all part of the mosaic. Progress is slow by any measure. The corridor's 2006 assessment counted over 8.5 million hectares; by 2015 the number had climbed to 21.5 million, largely by adding ocean area and expanding the inland footprint. The state of Espírito Santo - Brazil's smallest mainland state - has the densest concentration of protected areas per square kilometer in the country. Across the border in Bahia, the challenge is larger and the forest is rarer, which is precisely why the corridor matters most here. Every kilometer of reconnection matters because the alternative - isolated patches shrinking into extinction one species at a time - is the default, and the default is what the Atlantic Forest has been losing to for five centuries.