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Location Australia, Victoria
Central coordinates 144o 40.04' East  38o 14.25' South
IBA criteria A1, A4i
Area 3,377 ha
Altitude 0 - 10m
Year of IBA assessment 2009

BirdLife Australia

Summary The wetlands support significant numbers of the critically endangered Orange-bellied Parrot and the vulnerable Fairy Tern, and more than 1% of the world population of Blue-billed Duck, Chestnut Teal, Australian White Ibis, Straw-necked Ibis, Red-necked Stint and Silver Gull.

Site description The IBA is comprised of the Swan Bay area (including Lake Victoria, Freshwater Lake, Portarlington sewage works and Rabbit, Duck and Swan Islands), Mud Islands and a number of small man-made stacks, including Wedge Light, Popes Eye, South Channel Island and some navigation markers across southern Port Phillip Bay. Shorebirds regularly move between these locations to feed and roost but rarely move to the other areas of Port Phillip Bay, which are identified as separate IBAs. The habitat at Swan Bay consists of intertidal flats fringed by saltmarsh with a patch of coastal heathland to the north around Edwards Point. The natural habitat on the sand islands (Rabbit, Duck, Swan) at the entrance to the bay is dominated by saltmarsh, with some coastal heathland on Swan and Rabbit Islands. To the east of the bay lies Lake Victoria, a shallow, saline lake with extensive mudflats bordered by saltmarsh and sedgeland. To the north-west of Lake Victoria is Freshwater Lake, a smaller body of water, fringed by herbland, that is sometimes completely dry. The Mud Islands complex consists of a group of low, sandy islands with shrubland, saltmarsh, calcarenite outcrops and, at low tide, exposed mudflats. Popes Eye and South Channel Island are rock stacks that support some infrastructure. Wedge Light is a timber structure used for navigation purposes. Swan Bay and Mud Islands are within the Port Phillip Bay and Bellarine Peninsula Ramsar site.

Key Biodiversity The IBA is frequented by at least 20 species considered to be threatened or near threatened in Victoria (P. Menkhorst, unpubl. data) and regularly supports more than 20,000 waterbirds, including 4000 to 15,000 shorebirds and more than 10,000 nesting seabirds. In addition to the key species described above, the IBA supports significant proportions of the Victorian populations of Great Knot, Red Knot and Grey Plover; the largest breeding colonies in Victoria of White-faced Storm-Petrel (12,400 nesting burrows on Mud Islands and South Channel Island), Australian Pelican and Silver Gull; and important breeding colonies of Australasian Gannet (299 nests), Pied Cormorant, Crested Tern (2600 pairs on Mud Islands in 1999-2000) and Caspian Tern (20 pairs on Mud Islands)(Harris et al. 1980; Menkhorst 1988; Minton & Jessop 2000; Norman et al. 1998; P. Menkhorst, unpubl. data). Up to 808 Eastern Curlew and 1678 Sharp-tailed Sandpiper were recorded in the IBA in 1983-2004, but maximum counts exceeded thresholds in only two of 22 survey years and one of 22 survey years, respectively. Other waterbird species recorded in the IBA include the Banded Stilt (0 to 6000 birds in 1983-2004), Bar-tailed Godwit (219-2500 birds in 1983-2004 and 1500 birds on Mud Islands in 2006), Double-banded Plover (0-422 birds in 1983-2004), Pied Oystercatcher (37-84 birds in 1983-2004) and Red-capped Plover (82-342 birds in 1983-2004) (Barter 1992; AWSG, unpubl. data). Up to 28 Pacific Gulls have been recorded in winter on Mud Islands (P. Menkhorst, unpubl. data). Large numbers of Fairy Penguins feed in the open waters of Port Phillip Bay (Port of Melbourne Corporation 2004), and terns, including Little Tern and Common Tern, roost on Mud Islands (Lane et al. 1984). Striated Fieldwrens are frequently encountered in salt marsh habitat at Lake Victoria and around Swan Bay (Atlas of Australian Birds database; C. Tzaros pers. comm.).

Non-bird biodiversity: The Mud Islands complex supports one of the largest known stands of Austral Hollyhock (P. Menkhorst pers. comm. 2007). The southern waters of Port Phillip Bay contain populations of the Australian Fur Seal and Bottlenose Dolphin, as well as diverse marine ecosystems that have been included in marine reserves.

Populations of IBA trigger species

Species Season Period Population estimate Quality of estimate IBA Criteria IUCN Category
Chestnut Teal Anas castanea resident  1993-2006  1,300-4,000 individuals  good  A4i  Least Concern 
Blue-billed Duck Oxyura australis non-breeding  1993-2006  416 individuals  A1, A4i  Near Threatened 
Australian Ibis Threskiornis moluccus resident  1993-2007  12,000 nests  medium  A4i  Least Concern 
Straw-necked Ibis Threskiornis spinicollis resident  1993-2007  15,000 nests  medium  A4i  Least Concern 
Red-necked Stint Calidris ruficollis non-breeding  1983-2004  1,385-9,008 individuals  good  A4i  Near Threatened 
Larus novaehollandiae breeding  1959-1986  40,000-50,000 breeding pairs  good  A4i  Not Recognised 
Fairy Tern Sternula nereis resident  1993-2006  240 individuals  good  A1, A4i  Vulnerable 
Orange-bellied Parrot Neophema chrysogaster non-breeding  2000-2006  3-9 individuals  good  A1  Critically Endangered 

IBA Monitoring

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%) moderate to rapid deterioration medium
Human intrusions and disturbance recreational activities happening now majority/most of area/population (50-90%) no or imperceptible 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
Invasive & other problematic species, genes & diseases problematic native species/diseases - named species happening now some of area/population (10-49%) no or imperceptible deterioration low
Residential and commercial development housing and urban areas happening now small area/few individuals (<10%) moderate to rapid deterioration low

Protected areas

Protected area Designation Area (ha) Relationship with IBA Overlap with IBA (ha)  
Lonsdale Lakes Nature Conservation Reserve - Wildlife Reserve (no hunting) 193 protected area overlaps with site 165  
Mud Islands Nature Conservation Reserve - Wildlife Reserve (no hunting) 124 protected area contained by site 124  
Point Nepean National Park 470 protected area overlaps with site 1  
Port Phillip Bay and Bellarine Peninsula Wetlands of International Importance (Ramsar) 22,897 protected area overlaps with site 0  
Port Phillip Heads Marine National Park 3,580 protected area overlaps with site 2,216  
Swan Bay - Edwards Point Nature Conservation Reserve - Wildlife Reserve (no hunting) 279 protected area overlaps with site 217  


IUCN habitat Habitat detail Extent (% of site)
Artificial - terrestrial Other urban & industrial areas  minor
Coastline Intertidal mud, sand & salt flats; Lagoons; Sand cays, islets & bars; Sea cliffs, rocky shores & rocky islets  major
Shrubland Chenopod shrubs, samphire shrubs and forblands  minor
Wetlands (inland) Freshwater lakes & pools; Salt marshes  major

Land ownership Commonwealth; State Government; local council.

Land use

Land-use Extent (% of site)
nature conservation and research major
tourism/recreation minor
urban/industrial/transport minor

Protection status Various - see appropriate section.

Access/Land-Owner requests Access to South Channel Island is restricted. Access to some Commonwealth-owned parts of Mud Island is prohibited.

Acknowledgements The nomination was prepared by Kevin Wood. Peter Menkhorst (Department of Sustainability and Environment) and Chris Tzaros have supplied data and commented on this nomination.

References Barter, M. (1992) Changing wader numbers in Swan Bay, Victoria - a cause for concern? Stilt 21: 8-12.

Department of Sustainability and Environment (2003) Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site: Strategic Management Plan. Department of Sustainability and Environment, Victoria.

Geelong Field Naturalists Club (1997-2007) Geelong Bird Reports 1996-2006.

Harris, M.P., Deerson, D.M. and Brown, R.S. (1980) South Channel Island, Victoria. Corella 4: 100-101.

Hewish, M.J. (2003) Fauna Values of three Sub-coastal Wetlands on the Bellarine Peninsula: Lake Victoria, Freshwater Lake and St Leonards Salt Lagoon. Parks Victoria Technical Series Number 10.

Hewish, M.J.(2003) The waterbirds of Lake Victoria, a sub-coastal wetland on the Bellarine Peninsula. In the Geelong Bird Report 2002: 73-110.

Hewish, M., Mackenzie, R., Kroger, M., Kroger, H., Hart, B., Cameron, M. and Tribe, G. (2007) The Birds of Freshwater Lake. Geelong Bird Report.

Lane, B.A., Schulz, M. and Wood, K.L. (1984) Birds of Port Phillip Bay. Coastal Unit Technical Report No. 1, Ministry for Planning and Environment, Victoria.

Menkhorst, P.W. (1988) Mud Islands, Port Phillip Bay, Victoria. Corella 12: 72-77.

Minton, C. and Jessop, R. (2000) Tern banding by the Victorian Wader Study Group, 1999/2000. Australasian Seabird Bulletin 36: 10-11.

Norman, F.I., Milton, C.D.T., Bunce, A. and Govanstone, A.P. (1998) Recent changes in the status of Australasian Gannets Morus serrator in Victoria. Emu 98: 147-150.

Port of Melbourne Corporation (2004) Seabird and Marine Mammals Survey of Port Phillip Bay. Final Report Produced as part of EES for Channel Deepening Project.

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Recommended citation  BirdLife International (2016) Important Bird and Biodiversity Area factsheet: Swan Bay and Port Phillip Bay Islands. Downloaded from on 22/10/2016

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