Ecologists have needed four separate labels to describe what grows inside the park boundary: caatinga, semi-deciduous submontane forest, montane rainforest, and semi-deciduous lowland forest. All of it is officially filed under the Atlantic Forest biome, which is true in the way that a shipping label is true. What actually happens on this ground is a collision. Moist air rolling inland off the Atlantic runs out of moisture right about here, and the great coastal rainforest thins, shortens, and gives way to the drought-hardened caatinga of the interior. The terrain does not help matters — altitudes swing from 440 metres up past 1,111, so a single hillside can carry damp forest on its windward face and thorn scrub on its lee. Rainfall averages 1,300 millimetres a year. Temperatures run between about 14 and 26 °C, averaging 23. The mata de cipó, hung with woody vines and almost impenetrable on foot, is what grows in the middle of that argument.

That is the bird count recorded here so far, and it is the number that put Boa Nova on the international birding map. The reason is the collision itself. A birder walking the same morning can pick up dry-country caatinga specialists and humid-forest species that have no business being within a hundred kilometres of each other, because at Boa Nova their ranges overlap along a knife edge. The mata de cipó across the wider region has been credited with somewhere around 450 species. For a visiting birdwatcher, that means the target list is not merely long but strange — combinations you cannot assemble anywhere else in Brazil. The town of Boa Nova, elevated to city status on 6 August 1921 and home to roughly 14,000 people, has built a modest industry on this: scientific tourism, ecotourism, and the patient business of guiding foreigners with expensive optics down red dirt tracks before dawn.

Three endemic birds carry the region's conservation story. The slender antbird, Rhopornis ardesiacus, is threatened with extinction and effectively confined to the mata de cipó; it has become the emblem of the municipality. The Bahia spinetail, known locally as joão-baiano, and the Bahia tyrannulet, borboletinha-baiana — Phylloscartes beckeri, described only in the 1990s — are similarly narrow in range and similarly precarious. Their problem is not obscure. Mata de cipó grows on ground that is easy to clear and useful for cattle, and it had been vanishing for decades before anyone drew a line around what remained. Endemism is a wonderful thing to a visiting birder and a terrible thing to a species: it means there is no second population somewhere else to fall back on.

The decree of 11 June 2010 created two protected areas at once — the national park and, alongside it, the Boa Nova Wildlife Refuge. Together they lock up more than 27,000 hectares, roughly 31 percent of the municipality's territory, which is an unusually large bite of one town's land. The park is classed IUCN category II, the strictest tier that still permits recreation and interpretation, and it is administered by the Chico Mendes Institute for Biodiversity Conservation. Its stated purposes read like a list of everything the region needs at once: protect and regenerate the caatinga–Atlantic Forest transition, hold viable populations of endangered birds and mammals, restore watersheds, and support education, research, and ecological tourism. A management plan was approved in 2024. The park also slots into a larger design, the Central Atlantic Forest Ecological Corridor established in 2002, which tries to knit isolated fragments back into something a wide-ranging animal can actually cross.

Rain that falls on these hills leaves by a single route. The park drains into the Uruba River, which joins the Gongogi, which joins the Rio de Contas on its way to the Atlantic — a watershed that supplies towns well downstream of anyone who has heard of the slender antbird. Boa Nova, Dário Meira, and Manoel Vitorino all hold a piece of the park inside their boundaries, and the water argument is often the one that carries furthest with people who are unmoved by rare birds. Forest on a steep slope holds soil and meters out rainfall; cleared slope sends both downhill at once. In a region that alternates between drought and downpour, the case for keeping trees on the ridgelines does not need a life list to make it.