|Location||Australia, Northern Territory|
|Central coordinates||130o 48.80' East 11o 33.68' South|
|IBA criteria||A1, A2, A3, A4i|
|Altitude||0 - 205m|
|Year of IBA assessment||2009|
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Red Goshawk, with the Recovery Plan noting that ten pairs nested on average 8 km apart on Melville Island (D Baker-Gabb unpublished data), suggesting a territory size of c.50 km².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).
|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|
|2008||high||not assessed||not assessed|
|Medium - based upon reliable but incomplete / partially representative data|
|Agriculture and aquaculture||wood and pulp plantations (includes afforestation) - agro-industry plantations||happening now||some of area/population (10-49%)||moderate to rapid deterioration||high|
|Invasive & other problematic species, genes & diseases||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 area||Designation||Area (ha)||Relationship with IBA||Overlap with IBA (ha)|
|Kakadu||National Park||1,980,400||protected area contains site||783,781|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Artificial - terrestrial||Forestry plantations; Urban parks & gardens||minor|
|Forest||Eucalypt open forests; Eucalypt tall open forests; Eucalypt woodlands; Melaleuca forests & woodlands; Rainforest & vine thickets||major|
|Coastline||Intertidal mud, sand & salt flats; Mangrove wetlands||major|
Land ownership Tiwi ALT.
|Land-use||Extent (% of site)|
|Notes: Traditional use.|
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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