The site comprises several separate tidal
inlets, with a collective total area of 46 km2, that together form a diverse and extensive system of
wetlands providing habitat for large numbers of
waders, or shorebirds. The components include
Ralphs Bay, Mortimer Bay, Calvert's Lagoon, South Arm Neck, Barilla Bay,
Orielton Lagoon, the seaward side of the
Sorell Causeway over Pitt Water, and Pipe Clay Lagoon in
Frederick Henry Bay. These are mainly
estuarine sand and
mud flats with significant areas of
saltmarsh. The system is the southernmost destination for
migratory waders in the
East Asian – Australasian Flyway.
Birds The wetland system has been identified by
BirdLife International as an
Important Bird Area (IBA) because it supports well over 1% of the global population of
pied oystercatchers. Other waders using the wetlands in relatively large numbers include
red-necked stints,
curlew sandpipers,
Far Eastern curlews and
sooty oystercatchers.
Other animals The Sorell Causeway and the rocky shoreline of Pitt Water have the largest concentration of the
endemic viviparous sea star Patiriella vivipara. The saltmarsh around Barilla Bay is one of the few Tasmanian localities of the rare chequered blue butterfly (
Theclinesthes serpentata). ==References==