This EBA embraces northern Kimberley in the state of Western Australia, and the Top End in the Northern Territory. The habitats of the region include mangroves, monsoon rain forest (small patches, mainly on the coast) and eucalypt forest and woodland (in inland rugged ranges), but much the greatest part of the land area is, however, covered by variably grassy woodland, with desertic spinifex associations on very shallow substrates. In the north-east there lies a large sandstone escarpment, Arnhem Land, which is Aboriginal land (and is partly included within Kakadu National Park).

The boundary of the EBA has been drawn to include all records of restricted-range species from Blakers et al. (1984), and the area thus encompassed is very large. The vast majority of records lie, however, within core areas covering less than half this extent.

Together, the restricted-range species make use of all the main habitats included in this EBA, but they can be divided on the basis of their preferences: thus five species occur largely in mangroves and rain forest, three in eucalypt forest and grassy woodland, four in sandstone gorges and spinifex, and one in a mixture of different types.

Distribution patterns within the EBA vary, with one species being confined to the Kimberley, six to the Top End and the remaining six shared between the two regions, thereby combining two smaller areas of endemism into one large EBA. Species occurring in both Kimberley and the Top End either just range into one of the areas, or have a few scattered records only in one of the areas, or occur in limited habitat in both areas.

There are several other species which are largely confined to this EBA, but which are omitted because their estimated ranges are greater than 50,000 km²: Red-collared Lorikeet Trichoglossus rubritorquis, Northern Rosella Platycercus venustus, Sandstone Shrike-thrush Colluricincla woodwardi, Purple-crowned Fairywren Malurus coronatus and Long-tailed Finch Poephila acuticauda.

Kimberley Imperial-pigeon Ducula constans, which is also confined to this EBA, is treated as a form of the more widespread Pied Imperial-pigeon D. bicolor (following Christidis and Boles 1994, contra Sibley and Monroe 1993) and so is not included here as a restricted-range species.

The EBA is mostly uninhabited. However, it is farmed with stock, and in some areas there is little or no control over grazing or breeding (and increasing numbers of feral animals including cattle, donkeys, buffalo and pigs), and in consequence grassland is severely degraded. Fire has also degraded plant cover and led to species changes, especially as sustainable Aboriginal burning regimes (to encourage growth of new grass) are often no longer followed (WWF/IUCN 1994-1995). The small size of most patches of monsoon rain forest renders this habitat particularly vulnerable (Russell-Smith and Bowman 1992). Several of the rarer restricted-range species are thus considered Near Threatened, and Turnix castanota, whose populations appear to have declined, is classified as Vulnerable. Three subspecies endemic to this EBA are of particular note as all are treated as threatened by Garnett (1993): the Melville Island form of Masked Owl Tyto novaehollandiae melvillensis; the western Purple-crowned Fairy-wren Malurus coronatus coronatus, from restricted riverine habitat in Kimberley; and the northern Crested Shrike-tit Falcunculus frontalus whitei, which occurs at low density throughout the EBA.

The Endangered, but more widespread, Gouldian Finch Chloebia gouldiae, is also found in the EBA. Though abundant early in the twentieth century it is now only patchily distributed in north-west Queensland, the northern Northern Territory and the Kimberley region. The main problem appears to be an introduced parasitic mite, found in 60% of Northern Territory birds, which may prevent the population returning to its former numbers (Garnett 1993).

There are many protected areas in the EBA which partly cover the ranges of all its restricted-range species (Woinarski 1992). Particularly noteworthy is Kakadu National Park (18,000 km²), a World Heritage Site. An analysis based on the distributions of all mammals, landbirds and terrestrial reptiles has assigned priorities for the placement of future reserves, including ones in north and south-west Kimberley and eastern Arnhem Land (Woinarski 1992; see also Whitehead et al. 1992, Price et al. 1995).

Recommended citation
BirdLife International (2024) Endemic Bird Area factsheet: North-west Australia. Downloaded from https://datazone.birdlife.org/eba/factsheet/181 on 22/11/2024.