The South-East Asian ranges of two narrow-geographical range species, Germain’s Peacock Pheasant Polyplectron germaini (GPP) and Orange-necked Partridge Arborophila davidi (ONP) have been shrinking due to pressures from anthropogenic activities. To improve our knowledge of population densities of Germain’s Peacock Pheasant and the Orange-necked Partridge in their remaining habitats, their current and historical distribution range, and the contraction of their distribution range as a surrogate for population declines, we carried out line and point transect surveys in protected areas in southern Vietnam to estimate their density and subsequently model their habitat associations. Our results consistently showed that the density of the GPP was not significantly different among mosaic, evergreen, or mixed deciduous forests, but appeared to be notably lower in bamboo forest, while the density of the ONP was highest in evergreen and mosaic forests and lower in bamboo, with no detections in mixed-deciduous forest. GPP was mostly found close to water sources in mosaic, evergreen and mixed-deciduous forests. The presence of ONP was positively associated with elevation, evergreen and mosaic forest. Primary forest loss, mainly in the lowlands, within the ranges of both species was at least 70% over the last 70 years, suggesting that suitable habitats within the range of both species may have shrunk by at least 60–70%. In addition, a number of threats still occur in their remaining suitable habitats, making them increasingly vulnerable in the long-term, if conservation interventions, such as increased protection, are not implemented.