Current view: Text account
Site description (2008 baseline):
Site location and context
This IBA is made up of five discrete areas of tidal inlets east of Hobart that together comprise an extensive and diverse wetland system with abundant shorebirds. These are: Ralphs Bay, Mortimer Bay, Calvert's Lagoon, South Arm Neck, Barilla Bay, Orielton Lagoon, the seaward aspect of the causeway in Pitt Water, and Pipe Clay Lagoon in Frederick Henry Bay. The IBA is defined by all areas supporting significant numbers of feeding and roosting Pied Oystercatchers; colour-banding research has shown that individual oystercatchers and migratory shorebirds move regularly among these sites to feed and roost (Birds Tasmania unpubl. data). These are predominantly estuarine mud and sand flats with significant areas of saltmarsh. This system is the southernmost destination for migratory shorebirds in the East Asian-Australasian Flyway.
This IBA supports high numbers of migratory shorebirds, including Red-necked Stint regularly above 600, Eastern Curlew counts above 50, Curlew Sandpiper above 200 and Sooty Oystercatcher above 40. The South Arm IBA together with the Marion Bay IBA to the east are part of a network of wetlands which collectively support more than 1% of the global population of Red-necked Stint, but numbers within each individual IBA are below the 1% threshold. Other species which have been infrequently recorded within the IBA include Fairy Tern, Tasmanian Native-hen, Yellow Wattlebird and Striated Fieldwren (Atlas of Australian Birds database).
Non-bird biodiversity: Around the rocky shores of Pitt Water and along the Sorell Causeway is the largest concentration of the small endemic seastar Patiriella vivipara, one of the few viviparous sea stars known. The saltmarshes around Barilla Bay provide one of the few recorded Tasmanian localities of the rare Chequered Blue Butterfly.
Pressure/threats to key biodiversity
Removal of exotic species and greater control of human disturbance would improve this IBA. The marina proposal for Ralphs Bay (Lauderdale) would destroy large feeding and roosting areas used by 700+ Pied Oystercatchers.
Conservation responses/actions for key biodiversity
Onsite management funded for 2007 for habitat improvement, signage, fencing and exotic species removal for the Pitt Water-Orielton Lagoon Ramsar site. Long-term shorebird monitoring has generated data-sets for up to 40 years.
Several - see separate section for details.
Parts of four small protected areas are included but most of the IBA is private properties, some of which extend to low water mark.
Thanks to Eric Woehler as compiler. Thanks also to Priscilla Park, Mel Fazackerley, Lynne Sparrow, Sorell Council and Parks and Wildlife Service, NRM South for assistance with data and other information.
Recommended citation
BirdLife International (2024) Important Bird Area factsheet: South Arm (Australia). Downloaded from
https://datazone.birdlife.org/site/factsheet/south-arm-iba-australia on 20/12/2024.
