Walk up from the park's boundary and the forest changes with the elevation. Below 400 meters, lowland rainforest runs thick - figs, palms, the leaf canopy closing overhead at 30 meters, the air damp with 2,000 millimeters of annual rainfall. Higher, the canopy shortens. Above 800 meters, the trees become stunted, their trunks gnarled by steady wind and cloud. The high forest compensates with epiphytes - orchids, bromeliads, ferns, mosses - encrusting every branch. Serra das Lontras sits between the Una River and its tributaries to the north, the Javi, Pratinha, and Santo Antônio streams to the south. Eight of the Una's headwater springs rise inside the park boundary. Water from those springs still supplies the communities of São José da Vitória downslope.

The list of mammals protected inside the park reads like an inventory of what southern Bahia's forest used to hold everywhere and now holds almost nowhere. The golden-headed lion tamarin (Leontopithecus chrysomelas) is endemic to this region - a small, fire-orange-and-black primate that spends its life in the middle canopy. The maned sloth (Bradypus torquatus) is found only in Brazil's Atlantic Forest and is listed as vulnerable. The golden-bellied capuchin, the coastal black-handed titi, the bristle-spined rat - each of them confined to shrinking habitat fragments. Cougars still prowl these ridges. Among the 330 bird species are the harpy eagle, the ochre-marked parakeet, the red-browed amazon parrot, and the pink-legged graveteiro - a small brown bird described to science only in 1996, in these mountains, and still found virtually nowhere else.

The park came late. It was created by federal decree on 11 June 2010, more than a decade after Brazilian conservation scientists had identified the Serra das Lontras as one of the highest-priority sites in the Atlantic Forest. Administration falls to the Chico Mendes Institute for Biodiversity Conservation - ICMBio - named for the rubber tapper and organizer assassinated in Acre in 1988. Serra das Lontras became part of the Central Atlantic Forest Ecological Corridor, a landscape-scale conservation strategy created in 2002 to knit surviving forest fragments into a network large enough for breeding populations to persist. The forest inside the park has been selectively logged - you can see the signs in the uneven canopy - but most of it is recovering. That is the difference between this park and the cocoa farms and pasture that surround it: on one side of the boundary, the forest is climbing back. On the other, it is still being cut.