Restricted-range species
Most of the restricted-range species occur in forest with some in secondary habitats and plantations.
Today their distributions are very restricted, three species being single-island endemics (on Nuku Hiva, Ua Huka and Fatu Hiva) and four occurring in reasonable numbers on two islands only, although subfossils indicate that many species were once widespread in the archipelago (see Steadman 1989).

Threats and conservation
All the Marquesas islands have been devastated by overgrazing and fire, and much of the original dry forest has been reduced to grassland. Extensive damage has also been caused to upland forest on the larger islands by feral cattle, horses, goats, sheep and pigs, such that most of the native plants survive only in relict forest patches, and on some small islands little vegetation remains (WWF/IUCN 1994-1995).
Not surprisingly, most of the endemic bird species are considered threatened and Ptilinopus mercierii is almost certainly extinct. Ducula galeata (150-300 birds in 1993) is also close to extinction, and most other species are declining on at least some islands.
Although all species have suffered from habitat loss and degradation, Seitre and Seitre (1991, 1992) have identified rats (particularly black rat Rattus rattus) as the major threat to native birds. Thus they link the decline of Vini ultramarina on Ua Pou with an increase in rats following the 1983 hurricane, and they fear that Pomarea mendozae may also be susceptible, being now restricted to forest above 550 m where rats are fewer.
Introduced birds-such as the predatory Great Horned Owl Bubo virginianus and the very competitive Common Mynah Acridotheres tristisare so far restricted to Hiva Oa but are thought to have affected all native species on that island and Todirhamphus godeffroyi in particular (although the decline of this species is recent, while the myna was introduced in 1918 and the owl in 1927, and there may thus be other contributory factors). The demise of Ptilinopus mercierii on Hiva Oa was speculated to be due to the introduction of the owl (Holyoak and Thibault 1984), but Seitre and Seitre (1991) think that the earlier introduction of cats and rats, and even earlier hunting by Polynesians, may have been significant too. Illegal hunting remains the major threat to Ducula galeata, while both Pomarea iphis and P. whitneyi are considered threatened because of their tiny ranges, despite being relatively common within them.
Thibault (1988) identified the following areas as priorities for native landbird conservation: the high-altitude forests of Crêtes de Toovii on Nuku Hiva; the island of Fatu Huku; and the high-altitude forests of Cirque de Hohoi on Ua Pou. Ua Huka is the main stronghold for Vini ultramarina (c.800 individuals in 1991) and is therefore important too; 29 birds were relocated to Fatu Hiva during 1992-1994, and preliminary surveys indicate good survival and possible reproduction (Kuehler 1992, Kuehler et al. 1997).
Three islands are protected: Hatutaa, which is free of feral browsing mammals, and Eiao and Mohotoni which are both very degraded by feral sheep and pigs (Thibault 1989, Seitre and Seitre 1991).