|Most recent IBA monitoring assessment|
|Year of assessment||Threat score (pressure)||Condition score (state)||Action score (response)|
|2008||high||not assessed||not assessed|
|For more information about IBA monitoring please click here|
The IBA follows the boundaries of suitable vegetation for White-throated Grasswrens (heathlands, mixed heathlands and eucalypt, and mixed heathlands and rainforest as mapped by Blake 2004 and Woinarski et al. 2006) within the known and predicted range of this species as mapped by Noske (1992). This is approximately bounded by East Alligator Ranger Station to the northwest, 'Table Hill' vicinity (south-west of Maningrida) to the north-east, following the Mann River in the east to its headwaters, thence the Katherine River (from its headwaters) to Katherine Gorge National Park in the south, thence NNW to Kambolgie Creek-Mount Callanan vicinity, thence following the western escarpment to East Alligator Ranger Station. This includes much of the raised Arnhem Plateau where the habitat is dominated by sandstone plateaux and escarpments. The most important habitat for grasswrens is bare rock and spinifex on flat, often sparsely vegetated, high plateaux; heavily dissected escarpments and outliers supports less dense populations. The plateau is otherwise vegetated with open monsoonal savanna woodland and it also supports a high proportion of the Northern Territory’s rainforest including almost all of the rainforest dominated by the endemic tree Allosyncarpia ternata. About 25% of the IBA is located within Kakadu National Park, an outlier to the south is located within Nitmiluk (Katherine Gorge) National Park and much of the remainder is to be incorporated within the proposed Wardekken Indigenous Protected Area. There are no major population centres or roads within this rugged area but much is still used by the Traditional Owners.
The endangered Gouldian Finch, near threatened Grey Falcon, restricted-range Hooded Parrot and biome-restricted White-browed Robin are rare on the Arnhem Plateau (Atlas of Australian Birds database). The plateau also supports three endemic subspecies of three more widespread species: Banded Fruit-Dove (P. c. alligator is wholly restricted to the plateau), Helmeted Friarbird (P. b. ammintophila is wholly restricted to the plateau) and Variegated Fairy-Wren (M. l. dulcis is largely restricted to Arnhemland but integrades with M. l. assimilis to the south). The near threatened Chestnut-backed Buttonquail has been recorded in open woodland on sandstone (Woinarski et al. 1989) while the near threatened Partridge Pigeon may occur in non-sandstone plateau habitat.
Non-bird biodiversity: About 200 plant species are endemic to this massif and there is high endemicity of mammals, reptiles and invertebrates, including an endemic family of invertebrates (Woinarski et al. 2006; J. Woinarski in litt. 2007).
BirdLife International (2020) Important Bird Areas factsheet: Arnhem Plateau. Downloaded from http://www.birdlife.org on 19/02/2020.