About 5km south of Tuñón (or a 1km walk south from the Área Recreativa Buyera, where cars can park), the Senda del Oso reaches the Cercados Oseros, two compounds (one above the path, one below) housing two female Cantabrian brown bears considered unable to survive in the wild: Paca (born 1989) and Molina (born 2013). Of late both bears have been kept in the lower enclosure, where they're usually easily spotted from the Senda.
Paca and her sister Tola (who died in 2018) were orphaned as cubs by a hunter in 1989. Attempts at breeding from them, with a male bear, Furaco, brought from Cantabria’s Parque de la Naturaleza Cabárceno, were made without success in the 2000s. Molina arrived here as a young cub and failed to integrate back into the wild after being treated for life-threatening injuries.