Baiyer River Sanctuary, Protected nature reserve in Western Highlands Province, Papua New Guinea.

Baiyer River Sanctuary is a protected nature reserve covering 740 hectares of rainforest terrain across the Western Highlands region. The site spans elevations from 800 to 1200 meters and features river valleys, forest corridors, and wildlife rehabilitation facilities integrated throughout the landscape.

The reserve was opened on 13 January 1968 by the Australian administration of the time, not in 1967. It covers 740 hectares at elevations between 800 and 1200 metres. Over the years the area saw considerable unrest and the main buildings were burned down; renovation work was under way when the sources were written.

The reserve's name comes from the Baiyer River, which runs through the 740-hectare site. Its bird-of-paradise collection became a research resource: a hand-reared male Raggi's bird-of-paradise lived there 25 years, and the species bred in 1979, 1980 and 1983 with the same pair. A sickle-tailed bird-of-paradise bred there in 1984, likely a world first.

The sanctuary lies about 40 km from Mount Hagen; the first stretch of road is sealed, the rest a gravel track passable by car, and there are no direction signs. No facilities remain inside, as the buildings were burned down, though renovation is under way. Birdwatching requires long trails through the forest, and the source advises against tourist visits at this stage.

The frog Litoria oenicolen is known from only two specimens, both collected in this reserve, so it has not been recorded anywhere else. The reserve also held birds in captivity for study: a hand-reared male Raggi's bird-of-paradise lived there 25 years, and a sickle-tailed bird-of-paradise was bred in 1984, likely a world first.