|Location||Australia, Northern Territory|
|Central coordinates||131o 30.41' East 12o 29.16' South|
|IBA criteria||A1, A2, A3, A4i|
|Altitude||0 - 10m|
|Year of IBA assessment||2009|
Summary The floodplains support huge numbers of waterbirds, including more than 1% of the world populations of Magpie Goose (up to 800,000), Wandering Whistling-Duck, Pied Heron, Little Curlew, Eastern Curlew, Sharp-tailed Sandpiper, Red-necked Avocet. There are also large breeding colonies of over 30,000 mixed waterbirds, a significant population of Bush Stone-curlew and 11 restricted-range or savanna-biome-restricted species.
Site description The IBA includes the whole floodplains of the Adelaide and Mary Rivers. The Adelaide floodplain extends from south of the Arnhem Highway to the river mouth (The Narrows), mangroves at the base of Cape Hotham peninsula (Wilshire Creek area) and includes Chambers Bay. The Mary River Floodplain extends east to Swim Thrings Creek floodplain and Point Stuart, where it abuts the Alligator Rivers IBA. Floodplain wetlands within the site include Lake Finniss, Melacca and Black Jungle Swamps, the artificial Fogg and Harrison Dams, and various billabongs and lagoons. The unusual morphology of the Mary River floodplain contributes to rapid overtopping of levees and inundation of huge seasonal wetlands, even in years of relatively low rainfalls. Chambers Bay is dominated by sand/mudflats with samphire and mangrove or sand-dune coastlines. The IBA includes waterbird colonies references W23, W25, W27 and W46 in Chatto (2000a). The mean annual rainfall at Middle Point Research Station is approximately 1380 mm, mostly falling in December-March.
Key Biodiversity The waterbird colony on the Adelaide River 15km from its mouth is the largest colony in the Top End, with an estimated 30,000 birds including at least 1500 Great Egret, 6000 Intermediate Egret, 4500 Little Egret, 9500 Cattle Egret (Chatto 2000a). A high count of 33,000-41,000 waterbirds was made at Finniss Lake Lagoon during surveys by Kingsford et al. (2008). Eighty-eight waterbird species recorded on the Directory of Important Wetlands in Australia website database. High counts of waders along Chambers Bay include 2300 Black-winged Stilt, 1960 near threatened Black-tailed Godwit, 1525 Terek Sandpiper, 1650 Grey Plover and 1500 Whimbrel (Chatto 2000b, 2003 and in litt. in Bamford et al. 2008). Coastal mudflats and nearby areas apparently support in the order of 10,000 shorebirds at times and thousands of Oriental Pratincole on the floodplain, before the Wet sets in, and up to 2000 Comb-crested Jacana have been counted at Fogg Dam (August 1983) (DEWHA 2008). Twice, single flocks of more than 2000 Black-tailed Godwit have been observed on swamps 20 km inland from the coast (Chatto 2003). Other species rarely recorded in the IBA include the near threatened Australian Bustard, the restricted-range Yellow-rumped Mannikin and the Australian Little Bittern.
Non-bird biodiversity: A major breeding area for Saltwater Crocodile Crocodylus porosus.
|Species||Season||Period||Population estimate||Quality of estimate||IBA Criteria||IUCN Category|
|Magpie Goose Anseranas semipalmata||resident||-||800,000 individuals||medium||A4i||Least Concern|
|Wandering Whistling-duck Dendrocygna arcuata||resident||-||188,000 individuals||medium||A4i||Least Concern|
|Pied Heron Egretta picata||unknown||1990-2000||2,000 individuals||medium||A4i||Least Concern|
|Bush Thick-knee Burhinus grallarius||resident||1998-2008||uncommon||-||A1||Least Concern|
|Red-necked Avocet Recurvirostra novaehollandiae||unknown||-||3,000 individuals||poor||A4i||Least Concern|
|Little Curlew Numenius minutus||non-breeding||1990-2000||12,000 individuals||poor||A4i||Least Concern|
|Far Eastern Curlew Numenius madagascariensis||non-breeding||1990-2000||1,050 individuals||medium||A4i||Endangered|
|Sharp-tailed Sandpiper Calidris acuminata||non-breeding||1990-2000||2,500 individuals||medium||A4i||Least Concern|
|Varied Lorikeet Psitteuteles versicolor||unknown||1998-2008||uncommon||-||A3||Least Concern|
|Rainbow Pitta Pitta iris||resident||1998-2008||frequent||-||A2, A3||Least Concern|
|White-gaped Honeyeater Lichenostomus unicolor||resident||1998-2008||common||-||A3||Least Concern|
|Yellow-tinted Honeyeater Lichenostomus flavescens||resident||1998-2008||rare||-||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||unknown||1998-2008||rare||-||A3||Least Concern|
|Poecilodryas superciliosa||resident||1998-2008||rare||-||A3||Not Recognised|
|Australian Yellow White-eye Zosterops luteus||resident||1998-2008||rare||-||A3||Least Concern|
|Masked Finch Poephila personata||resident||1998-2008||uncommon||-||A3||Least Concern|
|Long-tailed Finch Poephila acuticauda||resident||1998-2008||uncommon||-||A3||Least Concern|
|2008||high||not assessed||not assessed|
|Medium - based upon reliable but incomplete / partially 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|
|Invasive & other problematic species, genes & diseases||invasive non-native/alien species/diseases - named species||happening now||some of area/population (10-49%)||moderate to rapid deterioration||high|
|Natural system modifications||fire & fire suppression - increase in fire frequency/intensity||happening now||small area/few individuals (<10%)||slow but significant deterioration||low|
|Protected area||Designation||Area (ha)||Relationship with IBA||Overlap with IBA (ha)|
|Adelaide River Foreshore||Other Conservation Area||254||protected area contained by site||240|
|Djukbinj||National Park (Aboriginal)||59,027||protected area overlaps with site||30,863|
|Fogg Dam||Conservation Reserve||1,569||protected area overlaps with site||687|
|Harrison Dam||Other Conservation Area||3,286||protected area contained by site||3,284|
|Lambells Lagoon||Other Conservation Area||423||protected area overlaps with site||1,421|
|Melacca Swamp||Other Conservation Area||2,301||protected area contained by site||2,315|
|IUCN habitat||Habitat detail||Extent (% of site)|
|Forest||Melaleuca forests & woodlands||minor|
|Wetlands (inland)||Riverine floodplains||major|
|Coastline||Intertidal mud, sand & salt flats; Mangrove wetlands||minor|
Land ownership Woolner, Koolpinyah and Kerlin Stations, Annaburroo, Marrakai, Opium Creek, Melaleuca and Swim Creek pastoral leases. Protected Areas jointly managed by the NT government and the Limilngan-Wulna people. Traditional Ownership.
|Land-use||Extent (% of site)|
|Notes: Traditional Use|
|nature conservation and research||major|
Protection status Several national parks and conservation areas.
Access/Land-Owner requests Much of this IBA is on private or Traditionally Owned land.
References Bamford, M., Watkins, D., Bancroft, W., Tischler, G. and Wahl, J. (2008) Migratory Shorebirds of the East Asian - Australasian Flyway; Population Estimates and Internationally Important Sites. Canberra, Australia: Wetlands International - Oceania.
Chatto, R. (2000a) 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. (2000b) A management strategy and protected areas system for coastal wildlife. (Documentation of selected sites in the Northern Territory of Australia which would qualify for nomination under the East Asian - Australasian Shorebird Site Network). Unpublished report, 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.
DEWHA (2008) Directory of Important Wetlands in Australia. http://www.environment.gov.au/water/publications/environmental/wetlands/database/ accessed 2008.
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.
Higgins, P.J. and Davies, S.J.J.F. (1996) Handbook of Australian, New Zealand and Antarctic Birds. Volume 3. Melbourne: OUP.
Kingsford, R.T., Halse, S.A. and Porter, J.L. (2008) Aerial surveys of waterbirds - assessing wetland condition. Final report to the National Land & Water Resources Audit. University of New South Wales, Sydney.
Jaensch, R. (1991) Lake Finnis: an internationally significant site for the Little Curlew. Stilt 25: 21.
Smith, F.T.H. (1971) Little Whimbrel in N.T. The Bird Observer 471: 5-6. 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 (2016) Important Bird and Biodiversity Area factsheet: Adelaide and Mary River Floodplains. Downloaded from http://www.birdlife.org on 28/08/2016
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