Vadim Viviani of the Federal University of Sao Carlos has been bringing students to Emas for more than three decades to catalogue what glows here. His 2023 survey in the Annals of the Entomological Society of America counted 51 bioluminescent beetle species across the region, 35 of them inside the park itself, making Emas the single most productive site in the study. The trend behind that number is grim. In the 1990s, Viviani has said, the mounds were full of light even out in the cattle pasture; today most of that pasture is sugarcane, and the light is gone. Soy and cane conversion, pesticide drift, and the spread of artificial lighting from nearby towns all appear in the paper as suspects. The spectacle survives largely because a line was drawn on a map in 1961, and because the land inside that line was never plowed.

Emas sits on the Serra do Caiapo, a plateau that lifts from around 400 metres in its valleys to roughly 880 metres on the tablelands. Water is the reason the park matters far beyond its fences. Protected inside it are the headwaters of the Jacuba and the Formoso, both tributaries of the Paranaiba, and the plateau serves as a northern recharge zone for the Guarani Aquifer, one of the largest freshwater reservoirs on the planet. The park also holds the only known expanse of a vegetation type Brazilian ecologists call hyperseasonal clean field, grassland that floods in the wet season and bakes in the dry. That rhythm governs everything. The climate here swings from humid to nearly semi-arid, with as many as five rainless months a year, and the grasses, the animals, and the beetles have all arranged their lives around the day the rain returns.

The park takes its name from the ema, the greater rhea, a flightless bird that crosses this open country in loose grey flocks. It is good company. Roughly 85 native mammal species have been recorded here, along with 400 bird species, which amounts to nearly half of all the birds known from the cerrado biome, plus 88 reptiles and 27 amphibians. Giant anteaters work the termite mounds by day. Maned wolves, long-legged and improbably orange, hunt the grassland at dusk. Giant armadillos, pampas deer, marsh deer, Brazilian tapir, both collared and white-lipped peccary, puma, ocelot, capybara and howler monkeys all have a claim on the place. Jaguars are here too, though barely: the population is thought to number only ten to twelve animals, and only about 40 percent of the reserve offers habitat they can actually use.

President Juscelino Kubitschek created the park by decree on 11 January 1961, in the years when Brasilia was rising a few hundred kilometres to the northeast and the interior was being opened in earnest. The boundaries were redrawn in 1972, and the reserve now covers about 1,320 square kilometres under the management of ICMBio, the federal conservation agency. In 2001, UNESCO inscribed Emas together with Chapada dos Veadeiros as the Cerrado Protected Areas World Heritage site, recognising a biome that is older and more species-rich than most tropical forests and far less famous than the Amazon that borders it. What surrounds Emas now explains the urgency of that listing. Beyond the boundary the land runs to soybeans in every direction, laid out in the geometric blocks of industrial agriculture. The park is not a fragment of a larger wild landscape. It is the landscape, and everything else has been converted.

Chapadao do Ceu, about 25 kilometres from the park, is the closest town, with banking, fuel, mechanics and a pharmacy. Mineiros, 110 kilometres from the park headquarters, is the regional centre and the place to find medical care. Neither is close to anything else. The reward for the drive is a landscape most visitors to Brazil never see: no canopy, no crowds, just grass to the horizon, termite mounds standing like chess pieces, and animals that are genuinely visible because there is nothing for them to hide behind. Come at the turn from dry season to wet, in late October or early November, and stay out after dark. The mounds will do the rest.