Current view: Text account
Site description (2008 baseline):
Site location and context
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.
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.
Pressure/threats to key biodiversity
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.
Conservation responses/actions for key biodiversity
A Strategic Management Plan has been prepared for the Port Phillip Bay and Bellarine Peninsula Ramsar site, which includes Swan Bay and Mud Islands. Management strategies for the major threats impinging on these components of the Ramsar site are discussed in this plan. In addition, a number of conservation actions are undertaken as part of the management programs for the protected marine areas and conservation reserves. The Australasian Wader Studies Group monitors wader numbers at the site.
Various - see appropriate section.
Commonwealth; State Government; local council.
Site access / Land-owner requests
Access to South Channel Island is restricted. Access to some Commonwealth-owned parts of Mud Island is prohibited.
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.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: Swan Bay and Port Phillip Bay Islands (Australia). Downloaded from
https://datazone.birdlife.org/site/factsheet/swan-bay-and-port-phillip-bay-islands-iba-australia on 23/12/2024.
