The IBA comprises the coastline from the Roper River to the Limmen Bight (for the shorebirds on intertidal flats) and the inland swamps south of the Roper River (which have large numbers of Black-winged Stilts) to the National Park boundary. The wetlands north of the Roper River are also important for birds but do not qualify for IBA status on current data. The main habitats are wide intertidal mudflats, scattered low samphire shrubland on otherwise bare coastal flats, and small areas (fringing channels) of low closed mangroves.
The IBA has supported up to 3038 near threatened Black-tailed Godwit (DEWHA 2008). A waterbird nesting colony near the mouth of the Roper River had about 2500 waterbirds including egrets, Pied Heron and cormorants (Chatto 2000 ref W055). At least ten other waterbird/seabird breeding rookeries also exist within the site, including the largest Pied Cormorant rookery (more than 2000 adults) and largest Little Tern (up to 100 nests) breeding colony in the Northern Territory. Other breeding colonies support large numbers of birds, including 10,000 Crested Tern and 5000 Roseate Tern. The highest number of shorebirds recorded over the site was 29,106 in April 1990; 24,938 were on mudflats north of Spillen Creek (i.e. mainly near Port Roper), the remainder were south of Spillen Creek. A total of 27,742 shorebirds for most of the site was recorded in February 1983; other counts have been below 5000 (DEWHA 2008; Chatto 2000; Chatto 2003; Chatto 2006). Sightings recorded in the Atlas of Australian Birds for 1998 to 2008 suggest the IBA supports small populations of the near threatened Australian Bustard and four tropical savanna biome-restricted species.
Non-bird biodiversity: High densities (> 5/km2) of dugong occur offshore between Limmen Bight River and Rosie Creek (seagrass beds), both in the Wet and the Dry. Medium densities of Saltwater Crocodile Crocodylus porosus occur in the Roper River estuary. Marine turtles (mix of species not yet described) use nest sites on offshore islands associated with the site (DEWHA 2008).
Pressure/threats to key biodiversity
More research is needed to identify threats and management actions but the area is likely to be susceptible to the impacts of sea-level rise and the impact of invasive alien plants e.g. Hymenachne.
Conservation responses/actions for key biodiversity
Limmen Bight and associated coastal floodplains are classified as a site of conservation significance by the Northern Territory Government (Harrison et al. 2009; Ward & Harrison 2009).
THe IBA overlaps the Limmen National Park.
Arnhemland and Marra ALT; may also include some of Saint Vidgeon, Nathan River and Lorella pastoral leases.
BirdLife International (2020) Important Bird Areas factsheet: Limmen Bight. Downloaded from
http://www.birdlife.org on 06/04/2020.