|Location||Australia, Northern Territory|
|Central coordinates||132o 32.32' East 12o 18.20' South|
|IBA criteria||A1, A2, A3, A4i|
|Altitude||0 - 10m|
|Year of IBA assessment||2009|
Summary The extensive floodplains were well surveyed in 1981-1984; extrapolating these maximum estimates to the whole IBA suggest that it supported five million waterbirds, including more than 1% of the world population of 22 species, and significant numbers of three near threatened species, and another 11 restricted-range or savanna-biome-restricted species.
Site description The IBA covers four large adjacent floodplains on the Wildman, Love and Alligator creeks, and the South Alligator, East Alligator, Magela, Cooper and Murgenella rivers. All are primarily seasonally flooded freshwater floodplains, with extensive areas of saltwater floodplains and permanent freshwater swamps. The rivers are tidal in their lower reaches and are associated with extensive tidal flats formed from riverborne mud. Wetland colonies in Chatto (2000) ref: W028, 29, 34, 35, 36, 37, 66. Waterbirds will also use the smaller wetlands inland of these floodplains, which are included in the adjacent Kakadu Savanna IBA. The climate is monsoonal with a hot wet season from November to March accounting for, on average, 90% of the annual rainfall which ranges from approximately 1300-1565 mm (Ramsar information sheet). Kakadu National Park is extremely popular, attracting some 210,000 international and national tourists visit the park each year, a large proportion of whom visit some part or other of the wetlands (Ramsar fact sheet).
Key Biodiversity Other high counts of birds (c.60% of IBA counted) included: 3000 White-necked Heron, 15,000 Australian White Ibis, 2,000 Darter, 1,000 Common Sandpiper and 2,300 Gull-billed Tern (Morton et al. 1989). Chatto (2000) listed numbers of nesting waterbirds at seven colonies, totalling at least 13,500 Intermediate Egret (but probably many 1000s more), 6,560 Great Egret, 1,080 Little Egret, 5,550 Cattle Egret (but probably many 1000s more), 7,250 Pied Heron, 1,500 Rufous Night-Heron, 3,800 Little Pied Cormorant and 4,200 Australian White Ibis. Chatto (2003) recorded 7,000 waders in Finke Bay in September 1993. The saline swamps and flats support unknown numbers of Yellow Chats which is otherwise very rare away from inland Australia.
Non-bird biodiversity: Wetlands species listed in the Ramsar notification include false water rat Xeromys myoides, golden-backed tree rat Mesembriomys macrurus, pig-nosed turtle Carettochelys insculpta, Mariana's hardyhead Craterocephalus marianae, exquisite rainbow fish Melanotaenia exquisita, Midgley's grunter Pingalla midgleyi and the frog Megistolotes lignarius.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Magpie Goose Anseranas semipalmata||unknown||1981-1994||1,600,000 individuals||medium||A4i||Least Concern|
|Plumed Whistling-duck Dendrocygna eytoni||unknown||1981-1994||50,000 individuals||medium||A4i||Least Concern|
|Wandering Whistling-duck Dendrocygna arcuata||unknown||1981-1994||400,000 individuals||medium||A4i||Least Concern|
|Radjah Shelduck Radjah radjah||unknown||1981-1994||20,000 individuals||medium||A4i||Least Concern|
|Green Pygmy-goose Nettapus pulchellus||unknown||1981-1994||50,000 individuals||medium||A4i||Least Concern|
|Pacific Black Duck Anas superciliosa||unknown||1981-1994||60,000 individuals||medium||A4i||Least Concern|
|Grey Teal Anas gracilis||unknown||1981-1994||50,000 individuals||medium||A4i||Least Concern|
|Black-necked Stork Ephippiorhynchus asiaticus||unknown||1981-1984||1,800 individuals||poor||A1, A4i||Near Threatened|
|Australian Ibis Threskiornis moluccus||unknown||1981-1994||15,000 individuals||medium||A4i||Least Concern|
|Straw-necked Ibis Threskiornis spinicollis||unknown||1981-1994||80,000 individuals||medium||A4i||Least Concern|
|Glossy Ibis Plegadis falcinellus||unknown||1981-1994||60,000 individuals||medium||A4i||Least Concern|
|Royal Spoonbill Platalea regia||unknown||1981-1994||35,000 individuals||medium||A4i||Least Concern|
|Mesophoyx intermedia||unknown||1981-1994||200,000 individuals||medium||A4i||Not Recognised|
|Pied Heron Egretta picata||unknown||1981-1994||50,000 individuals||medium||A4i||Least Concern|
|Australian Pelican Pelecanus conspicillatus||unknown||1981-1994||50,000 individuals||medium||A4i||Least Concern|
|Australian Bustard Ardeotis australis||unknown||1998-2008||212 individuals||medium||A1||Least Concern|
|Brolga Antigone rubicunda||unknown||1981-1994||24,000 individuals||medium||A4i||Least Concern|
|Bush Thick-knee Burhinus grallarius||resident||1998-2008||frequent||-||A1||Least Concern|
|Himantopus leucocephalus||unknown||1981-1994||100,000 individuals||medium||A4i||Not Recognised|
|Vanellus miles||unknown||1981-1994||80,000 individuals||medium||A4i||Not Recognised|
|Comb-crested Jacana Irediparra gallinacea||unknown||1981-1994||25,000 individuals||medium||A4i||Least Concern|
|Little Curlew Numenius minutus||non-breeding||1981-1994||300,000 individuals||medium||A4i||Least Concern|
|Sharp-tailed Sandpiper Calidris acuminata||non-breeding||1990-2002||4,900 individuals||medium||A4i||Least Concern|
|Australian Pratincole Stiltia isabella||unknown||1981-1994||30,000 individuals||medium||A4i||Least Concern|
|Whiskered Tern Chlidonias hybrida||non-breeding||1981-1994||45,000 individuals||medium||A4i||Least Concern|
|Varied Lorikeet Psitteuteles versicolor||unknown||1998-2008||uncommon||-||A3||Least Concern|
|Northern Rosella Platycercus venustus||resident||1998-2008||uncommon||-||A3||Least Concern|
|Rainbow Pitta Pitta iris||resident||1998-2008||uncommon||-||A2, A3||Least Concern|
|White-gaped Honeyeater Lichenostomus unicolor||resident||1998-2008||abundant||-||A3||Least Concern|
|Silver-crowned Friarbird Philemon argenticeps||resident||1998-2008||uncommon||-||A3||Least Concern|
|Bar-breasted Honeyeater Ramsayornis fasciatus||resident||1998-2008||uncommon||-||A3||Least Concern|
|Banded Honeyeater Certhionyx pectoralis||resident||1998-2008||uncommon||-||A3||Least Concern|
|Poecilodryas superciliosa||resident||1998-2008||uncommon||-||A3||Not Recognised|
|Australian Yellow White-eye Zosterops luteus||resident||1998-2008||uncommon||-||A3||Least Concern|
|Masked Finch Poephila personata||resident||1998-2008||uncommon||-||A3||Least Concern|
|Long-tailed Finch Poephila acuticauda||resident||1998-2008||frequent||-||A3||Least Concern|
|2008||high||not assessed||not assessed|
|Good - based on reliable and complete / representative data|
|Climate change and severe weather||storms and floods||likely in long term (beyond 4 years)||some of area/population (10-49%)||slow but significant deterioration||medium|
|Energy production and mining||mining and quarrying||happening now||small area/few individuals (<10%)||slow but significant deterioration||low|
|Invasive & other problematic species, genes & diseases||invasive non-native/alien species/diseases - named species||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 overlaps with site||248,294|
|Kakadu National Park||World Heritage Site||1,980,400||protected area overlaps with site||240,333|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Forest||Melaleuca forests & woodlands||major|
|Shrubland||Chenopod shrubs, samphire shrubs and forblands||minor|
|Coastline||Intertidal mud, sand & salt flats; Mangrove wetlands||minor|
|Wetlands (inland)||Riverine floodplains||major|
Land ownership Kakadu NP owned by Traditional Owners and managed in partnership with National Parks; wetlands to east owned by Arnhemland ALT.
|Land-use||Extent (% of site)|
|Notes: Traditional Use|
|nature conservation and research||major|
Protection status IBA overlaps Kakadu and Mary River National Parks.
Access/Land-Owner requests Much of this IBA is on private or Traditionally Owned land.
References Bamford, M.J. (1990). RAOU survey of migratory waders in Kakadu National Park: Phase III. Report to ANPWS. RAOU Report No. 70.
Chatto, R. (2000) Waterbird breeding colonies in the Top End of the Northern Territory. Technical Report 69, Parks and Wildlife Commission of the Northern Territory, Palmerston.
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.
Chatto, R. (2006) The distribution and status of waterbirds around the coast and coastal wetlands of the Northern Territory. Technical Report 76, Parks and Wildlife Commission of the Northern Territory, Palmerston.
A Directory of Important Wetlands in Australia (accessed March 2007) Kakadu National Park - NT017 Kakadu National Park management plans (website accessed March 2007) http://www.environment.gov.au/parks/kakadu/parkjointmang/mangprograms/index.html
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. Morton, S.R., Brennan, K.G. and Armstrong, M.D. (1989) Distribution and abundance of waterbirds on the Alligator Rivers Region, Northern Territory. Report to the Australian National Parks and Wildlife Service. Office of supervising scientist for the Alligator region, Jabiru, NT.
Smyth, D. (1995) Coming out Bright. An audit of research conducted in KNP 1992-1995. Australian Nature Conservation Agency, Jabiru. 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.
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Recommended citation BirdLife International (2015) Important Bird Areas factsheet: Alligator Rivers Floodplains. Downloaded from http://www.birdlife.org on 30/07/2015
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