Mbaracayu Forest Nature Reserve (MFNR) is privately owned by the non-governmental organisation Fundación Moisés Bertoni (FMB) and is one of the largest remaining tracts of privately owned dense humid sub-tropical forest in South America.
Tapir (Tapirus terrestris), Marsh Seedeater (Sporophila palustris), Dark-throated Seedeater (Sporophila ruficollis), Chestnut Seedeater (Sporophila cinnamomea), Broad-snouted Caiman (Caiman latirostris) and Southern Toad-headed Turtle (Mesoclemys vanderhaegei) are threatened and rare species living in the region. Many migratory birds use the area as resting place such as Lesser Yellowlegs (Tringa flavipes), Solitary Sandpiper (Tringa Solitaria), Wilson´s Phalarope (Phalaropus tricolor) as well as the before mentioned three different species of seedeater.