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Location Australia, Northern Territory
Central coordinates 130o 48.80' East  11o 33.68' South
IBA criteria A1, A2, A3, A4i
Area 783,781 ha
Altitude 0 - 205m
Year of IBA assessment 2009

BirdLife Australia



Summary The Tiwi Islands support exceptionally high densities of the vulnerable Red Goshawk and near threatened Partridge Pigeon and Bush Stone-curlew. They also support populations of three restricted-range species, nine tropical savanna-restricted species, and many migratory shorebirds including more than 1% of the world's Great Knots.

Site description The Tiwi Islands, consisting of Melville and Bathurst Islands, are the largest landmass off the Australian coast after Tasmania. They have been isolated from the mainland since the last ice age and are largely covered with eucalypt forest on a gently sloping lateritic plateau. Small rainforest patches occur in association with perennial freshwater springs, and mangroves surround numerous inlets. The climate is monsoonal, the wet season from November to April having the highest rainfall in the Northern Territory, with an average of at least 1400 mm per year. Two threatened species, the Red Goshawk and the Partridge Pigeon, are exceptionally common on the islands compared to the rest of their range. Red Goshawks are most often found in extensive open forest, open woodlands and riparian vegetation dominated by mature Eucalyptus tetrodonta, Woollybutt Eucalyptus miniata, and Cadjeputs Melaleuca leucadendron (Aumann and Baker-Gabb 1991, Woinarski et al. 2000). Several endemic subspecies are also threatened, including those of the Masked Owl and the Hooded Robin. Plantation forestry operations of Acacia mangium may eventually cover 10% of the islands but it is currently intended that the remainder of the islands remain uncleared. Populations of threatened birds are being monitored as part of the forestry operations and there is active management of other threatening processes.

Key Biodiversity There is a high level of endemism at the subspecific level on the Tiwi Islands. Of these, the Masked Owl Tyto novaehollandiae melvillensis is considered Endangered and the Hooded Robin Melanodryas cucullata melvillensis is Endangered and may be Extinct, as there have been no records for ten years despite searching. The islands are a stronghold for Red Goshawk, with the Recovery Plan noting that ten pairs nested on average 8 km apart on Melville Island (D Baker-Gabb unpublished data), suggesting a territory size of c.50 km². This contrasts with one measured home range size of c.200 km² on the mainland (Aumann and Baker-Gabb 1991) and led Woinarski et al. (2000) to suggest there were 40-80 pairs on the islands. Chatto (2003) estimated 40,000 mixed waders in October 1993, which is likely to include at least 1% of the flway populations of Great Knot, Red-necked Stint, Greater Sand Plover and Bar-tailed Godwit.

Non-bird biodiversity: Tiwi Islands IBA supports a range of endemic flora, particularly associated with rainforest patches, including 64 species that are either threatened or data deficient and 11 species that are endemic to the Tiwi Islands. It also supports a number of other threatened animals including Brush-tailed Tree-rat Conilurus penicillatus, Northern Brush-tailed Phascogale Phascogale pirata, False Water-rat Xeromys myoides and the Endangered Butlers Dunnart Sminthopsis butleri. Several species of threatened sea turtle nest on the beaches (Woinarski et al. 2004a,b,c).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Red Goshawk Erythrotriorchis radiatus resident  2006  80-160 individuals  medium  A1  Near Threatened 
Chestnut Rail Eulabeornis castaneoventris resident  uncommon  A2  Least Concern 
Beach Thick-knee Esacus magnirostris resident  26 breeding pairs  medium  A1  Near Threatened 
Bush Thick-knee Burhinus grallarius resident  1998-2008  frequent  A1  Least Concern 
Great Knot Calidris tenuirostris non-breeding  1990-2002  12,000 individuals  poor  A4i  Vulnerable 
Partridge Pigeon Geophaps smithii resident  1,000-2,500 individuals  medium  A1, A2, A3  Vulnerable 
Varied Lorikeet Psitteuteles versicolor resident  1998-2008  common  A3  Least Concern 
Northern Rosella Platycercus venustus resident  1998-2008  common  A3  Least Concern 
Rainbow Pitta Pitta iris resident  1998-2008  uncommon  A2, A3  Least Concern 
White-gaped Honeyeater Lichenostomus unicolor resident  1998-2008  frequent  A3  Least Concern 
Yellow-tinted Honeyeater Lichenostomus flavescens resident  1998-2008  common  A3  Least Concern 
Silver-crowned Friarbird Philemon argenticeps resident  1998-2008  abundant  A3  Least Concern 
Bar-breasted Honeyeater Ramsayornis fasciatus resident  1998-2008  frequent  A3  Least Concern 
Australian Yellow White-eye Zosterops luteus resident  1998-2008  common  A3  Least Concern 
Masked Finch Poephila personata unknown  1998-2008  rare  A3  Least Concern 

IBA Monitoring

2008 high not assessed not assessed
unset
Medium - based upon reliable but incomplete / partially representative data

Agricultural expansion and intensification wood and pulp plantations (includes afforestation) - agro-industry plantations happening now some of area/population (10-49%) moderate to rapid deterioration high
Invasive and other problematic species and genes invasive non-native/alien species/diseases - named species happening now some of area/population (10-49%) slow but significant deterioration medium
Natural system modifications fire & fire suppression - increase in fire frequency/intensity happening now majority/most of area/population (50-90%) slow but significant deterioration high

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Kakadu National Park 1,980,400 protected area contains site 783,781  

Habitats

IUCN habitat Habitat detail Extent (% of site)
Artificial - terrestrial Forestry plantations; Urban parks & gardens  minor
Grassland Tussock grasslands  2%
Forest Eucalypt open forests; Eucalypt tall open forests; Eucalypt woodlands; Melaleuca forests & woodlands; Rainforest & vine thickets  major
Wetlands (inland) Ephemeral  2%
Coastline Intertidal mud, sand & salt flats; Mangrove wetlands  major

Land ownership Tiwi ALT.

Land use

Land-use Extent (% of site)
other major
Notes: Traditional use.
forestry minor

Access/Land-Owner requests Traditionally owned land.

Acknowledgements John Woinarski, Kate Hadden, Bill Headley, Tiwi Land Council. The nomination, drafted by Stephen Garnett and David Baker-Gabb, was endorsed by Tiwi Land Council in 2006.

References Aumann, T. and Baker-Gabb, D.J. (1991) The ecology and status of the Red Goshawk in northern Australia. RAOU Report No.75, Melbourne.

Baker-Gabb, D.J. (2005) Recovery Plan for the Red Goshawk Erythrotriorchis radiatus, 2006 - 2011. Elanus Pty Ltd, Melbourne.

Chatto, R. (2003) The distribution and status of shorebirds around the coast and coastal wetlands of the Northern Territory. Technical Report 73, Parks and Wildlife Commission of the Northern Territory, Palmerston.

Harrison, L., McGuire, L., Ward, S. Fisher, A., Pavey, C., Fegan, M. and Lynch, B. (2009) An inventory of sites of international and national significance for biodiversity values in the Northern Territory. Department of Natural Resources, Environment, the Arts & Sport, Darwin, NT.

Ward, S. and Harrison, L. (2009) Recognising sites of conservation significance for biodiversity values in the Northern Territory. Department of Natural Resources, Environment, the Arts & Sport, Darwin, NT.

Woinarski, J., Brennan, K., Hempel, C., Firth, R. and Watt, F. (2000) Biodiversity Conservation on the Tiwi Islands: plants, vegetation types and terrestrial vertebrates on Melville Island. A report to the Tiwi Land Council.

Woinarski, J., Brennan, K., Cowie, I.A., Kerrigan, R. and Hempel, C. (2003a) Biodiversity Conservation on the Tiwi Islands, Northern Territory. Part 1. Environments and plants, Department of Infrastructure Planning and Environment, Darwin.

Woinarski, J., Hadden, K., Hicks, J. and McLeod, D. (2003b) Biodiversity Conservation on the Tiwi Islands, Northern Territory: Part 3. Management and planning for biodiversity conservation., Department of Infrastructure Planning and Environment, Darwin.

Woinarski, J., Brennan, K., Hempel, C., Armstrong, M. and Milne, D. (2003c) Biodiversity Conservation on the Tiwi Islands, Northern Territory. Part 2. Fauna, Department of Infrastructure Planning and Environment, Darwin.

Woinarski, J. (2004) National Multi-species Recovery Plan for the Partridge Pigeon (eastern subspecies) Geophaps smithii smithii, Crested Shrike-tit (northern subspecies) Falcunculus (frontatus) whitei, Masked Owl (north Australian mainland subspecies) Tyto novaehollandiae kimberli, and Masked Owl (Tiwi Islands subspecies) Tyto novaehollandiae melvillensis, 2004-2009. Northern Territory Department of Infrastructure Planning and Environment, Darwin.

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Recommended citation  BirdLife International (2014) Important Bird Areas factsheet: Tiwi Islands. Downloaded from http://www.birdlife.org on 29/12/2014

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