A handful of protected areas are privately owned. Reservas Silvestres Privadas (Private Wilderness Reserves) are entirely private landholdings granted protected status through the SINAP project. Interested landowners must meet a number of criteria and present an approved management plan.
Such reserves are usually near other parks or reserves, contain substantial vegetation and wildlife, and are often a part of some biological corridor. At this early point in the game, they are in varying stages of developing their tourism infrastructures.
The original six private reserves are Montibelli near Chocoyero, Domitila outside Nandaime [1], La Maquina on the road to the coast from Diriamba [2], Toromixcal in San Juan del Sur [3], César Augusto in Jinotega, and Greenfields near Pearl Lagoon. Look for them in the appropriate regional chapters.
Links:
[1] http://www.moon.com/destinations/nicaragua/ometepe-and-rivas/near-rivas/nandaime-and-domitila-wildlife-reserve
[2] http://www.moon.com/destinations/nicaragua/masaya/the-pueblos-blancos-and-carazo/carazo
[3] http://www.moon.com/destinations/nicaragua/southwest-coast