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Location Australia, Northern Territory
Central coordinates 134o 35.34' East  12o 7.57' South
IBA criteria A4i
Area 43,224 ha
Altitude 0 - 10m
Year of IBA assessment 2009

BirdLife Australia



Summary These floodplains have supported more than 1% of the world population of Pied Heron, Brolga and Great Knot. The large numbers of shorebirds recorded at Boucaut Bay include more than 1% of the world population of Great Knot and Pied Oystercatcher.

Site description The boundary follows the coastal floodplains of the Cadell and Blyth rivers, and the adjacent length of Boucaut Bay. This IBA is situated between the Maningrida community to the west and the Milingimbi community to the east. The seasonal flooding comes from flows down the Blyth and Cadell Rivers and various creeks. Most of the floodplain is more than 1 m deep in wetter years.

Key Biodiversity Boucaut Bay has supported up to 5000 near threatened Black-tailed Godwit (Chatto 2003). The floodplains also support large numbers of other waterbirds including counts of 1000 Little Pied Cormorant, 1000 Great Egret, and total counts of waterbirds include 26,000 in 80-90% of area counted; 19,500 in 80-90% of area counted in 1992; 17,000 in 25-50% of area counted in 1999 (Chatto 2003). A waterbird nesting colony in coastal mangroves had 2000 herons, including 1000 Pied Herons in 1999; and one on the Blyth River had 1000 herons and 1000 Little Pied Cormorants in 1999 (Chatto 2000 waterbird breeding colony ref W039 and W045). More than 15,000 waders regularly recorded in the area 10 km either side of the mouth of the Blyth River; the most abundant shorebird species are Great Knot (up to 4895), Black-tailed Godwit (1099), Red-necked Stint (722) and Pied Oystercatcher (up to 311). At least 10,000 Magpie Geese and 100,000 whistling-ducks occur at times in the Maningrida-Milingimbi district; a large proportion of these birds would use the Blyth-Cadell floodplain. The near threatened Asian Dowitcher is a non-breeding visitor in small numbers, with a count of 15 in 1990 (DEWHA 2008). Chestnut Rails have been recorded on the floodplains but their local abundance is poorly known (Chatto 2006). Other species recorded at the site include the biome-restricted White-gaped Honeyeater, Bar-breasted Honeyeater and Long-tailed Finch (Atlas of Australian Birds database).

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Pied Heron Egretta picata resident  1990-2000  1,000-4,895 individuals  medium  A4i  Least Concern 
Brolga Antigone rubicunda unknown  2000-2007  800-3,000 individuals  poor  A4i  Least Concern 
Pied Oystercatcher Haematopus longirostris unknown  1990-2001  311 individuals  poor  A4i  Least Concern 
Great Knot Calidris tenuirostris non-breeding  1990-2001  5,500 individuals  medium  A4i  Vulnerable 

IBA Monitoring

2008 medium not assessed not assessed
unset
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 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

Habitats

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  major
Wetlands (inland) Riverine floodplains  major

Land ownership xxx

Land use

Land-use Extent (% of site)
other major
Notes: Traditional Use

Access/Land-Owner requests This IBA is on traditionally owned land.

References 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.

DEWHA (2008) Directory of Important Wetlands in Australia (NT022) 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.

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 (2014) Important Bird Areas factsheet: Cadell and Blyth Floodplains. Downloaded from http://www.birdlife.org on 19/12/2014

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