Swan Bay and Port Phillip Bay Islands (23932)
Australia, Australasia

Site overview

KBA status: confirmed

Global KBA criteria: A1b, B1, D1a

Year of last assessment: 2009

National site name: Swan Bay and Port Phillip Bay Islands

Central coordinates: Latitude: -38.2375, Longitude: 144.6673

System: marine, terrestrial

Elevation (m): 0 to 10

Area of KBA (km²): 33.29184

Protected area coverage (%): 86.28

KBA classification: Global

Legacy site: Yes

Site details

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.

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: 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.

Other site values: Commonwealth; State Government; local council. Access to South Channel Island is restricted. Access to some Commonwealth-owned parts of Mud Island is prohibited.

Habitats

Land use: nature conservation and research | tourism/recreation | urban/industrial/transport

IUCN Habitat	Coverage %	Habitat detail
Marine Intertidal	45
Artificial - Terrestrial	5
Shrubland	5
Marine Coastal/Supratidal	45

Threats

Summary of threats to biodiversity at KBA: Saltmarshes and adjacent damp areas of fields should be managed for Orange-bellied Parrots by fencing and allowing plants to grow and seed. Nesting colonies of Fairy Terns should be monitored and protected from foxes and people where necessary.

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
Invasive & other problematic species, genes & diseases	Problematic native species/diseases	Named species	Ongoing
Residential & commercial development	Housing & urban areas		Ongoing
Human intrusions & disturbance	Recreational activities		Ongoing
Climate change & severe weather	Storms & flooding		Only in the future

Additional information

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.