Alligator Rivers Floodplains (23434)
Australia, Australasia
Site overview
KBA status: confirmed
Global KBA criteria: B1, D1a
Year of last assessment: 2009
National site name: Alligator Rivers Floodplains
Central coordinates: Latitude: -12.3033, Longitude: 132.5387
System: freshwater, marine, terrestrial
Elevation (m): 0 to 10
Area of KBA (km2): 3681.81219
Protected area coverage (%): 65.52
KBA classification: Global
Legacy site: Yes
Site details
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).
Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.
Additional 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.
Other site values: Kakadu NP owned by Traditional Owners and managed in partnership with National Parks; wetlands to east owned by Arnhemland ALT. Much of this IBA is on private or Traditionally Owned land.
Habitats
Land use: nature conservation and research
| IUCN Habitat | Coverage % | Habitat detail |
|---|---|---|
| Shrubland | 5 | |
| Wetlands(Inland) | 45 | |
| Forest | 45 | |
| Marine Intertidal | 5 |
Threats
Summary of threats to biodiversity at KBA: The National Park has a comprehensive management plan but effective control of invasive alien species, notably Mimosa pigra, requires additional funding. The adjacent floodplains outside the National Park should be managed in the same way, as these are contiguous for both birds and invasive alien species.
| Threat level 1 | Threat level 2 | Threat level 3 | Timing |
|---|---|---|---|
| Invasive & other problematic species, genes & diseases | Invasive non-native/alien species/diseases | Named species | Ongoing |
| Energy production & mining | Mining & quarrying | Ongoing | |
| Climate change & severe weather | Storms & flooding | Only in the future |
Additional information
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.