Mbaracayú is 64,405 hectares of Atlantic forest on the Brazilian border in Canindeyú, and it is the best-protected large forest left in Paraguay — not because the state protects it, but because the Fundación Moisés Bertoni bought it in 1991 and has held it ever since. UNESCO made it a biosphere reserve in 2000, the first in the country.
The numbers are the reason to come: around 400 bird species, including bare-throated bellbirds whose call carries a kilometre through the forest, plus jaguar, tapir, giant armadillo and white-lipped peccary. It sits on the transition between Atlantic forest and cerrado, which is why the species list is longer than the size suggests. Serious neotropical birders put this on the same list as Itatiaia and Iguazú.
Two indigenous peoples live inside the reserve: Aché communities, who were hunter-gatherers here within living memory and retain hunting rights, and Guaraní farming communities. The foundation also runs an agricultural secondary school for girls from the surrounding countryside, which is unusual and worth knowing about — the reserve is a working social project, not just a fence.
Getting there is the hard part. It is about 250 km from Asunción via Curuguaty and Villa Ygatimí, the last stretch unpaved and impassable after real rain. Visits go through the foundation, which runs the field station and the accommodation; turning up unannounced does not work. Dry season, May to September.