The U.N. World Heritage Committee announced the decision at a meeting at UNESCO headquarters in Paris.
The Rio Platano Biosphere Reserve in Honduras was put back on the endangered list four years after having the protective status lifted because of the Honduran government's previous success in controlling incursions, a U.N. release reported Wednesday.
The committee said the Tropical Rainforest Heritage of Sumatra in Indonesia, "has been placed on the Danger List to help overcome threats posed by poaching, illegal logging, agricultural encroachment, and plans to build roads through the site."
The 2.5-million hectare Sumatran forest was designated a World Heritage site in 2004 for its biodiversity, while the Rio Platano Biosphere Reserve, home to an indigenous population that has preserved its traditional way of life in the rainforest, was designated in 1979.
It had been previously place on the Danger List between 1996 and 2007.
The danger list helps "focus the efforts of government departments, civil society and international cooperation" on the threatened areas, UNESCO said.