Wetlands Australia 32: Coastal wetlands provide a home away from home to Australia’s migratory shorebirds
Author: Amanda Lilleyman (Threatened Species Recovery Hub, National Environment Science Programme, Charles Darwin University)
Coastal wetlands provide a home to a rich mix of biodiversity, including migratory shorebirds that spend more than half of the year in Australia and the rest of the time in the northern hemisphere where they breed. As coastal wetlands are under increasing pressure and threats, so too are the animals that rely on them.
The far eastern curlew (Numenius madagascariensis) has experienced one of the most acute declines of any Australian migratory shorebird species. Currently little is known about its exact feeding and roosting habitat requirements while it is on the non-breeding grounds. In our project we are tracking the local and international movements of this globe-trotting shorebird as it makes its way through the East Asian-Australasian Flyway.
Far Eastern Curlew
The curlew and the other 36 species of migratory shorebirds that visit Australia call wetlands home for up to eight months each year. Many species of shorebird use coastal wetlands throughout most of their annual migration. From our GPS tracking of the critically endangered curlew, we are finding that the species has a high degree of site fidelity, with many individuals travelling from roost sites where birds rest and digest food at high tide, to intertidal feeding grounds nearby where birds feed on shellfish. Our tracking in Darwin Harbour in the Northern Territory is showing that the species uses coastal saltmarsh in amongst mangrove forests throughout both spring and neap tide cycles.
These saltmarsh areas are not only important to migratory shorebirds, but they are also culturally important to the local Indigenous Traditional Owners, the Larrakia People or Saltwater People. Within saltmarsh areas is evidence of traditional hunting from the nearby coastline with shell middens made up of roughback cockles (Anadara granosa), formed over thousands of years. This overlap between culture and biodiversity places importance on the protection of coastal wetlands which are threatened by sea-level rise and further urbanisation.
In addition to our GPS tracking of the curlew, we visit coastal wetlands, mangrove forests and an artificial wetland to document changes to the habitat. One thing we are finding is the ecological succession of both freshwater wetlands and saltmarsh areas. We have observed the expansion of mangrove seedlings across saltmarsh areas and also the increased growth of vegetation in an artificial freshwater wetland.
Through our work we are aiming to provide recommendations for improved management of migratory shorebirds in Darwin Harbour, which we hope will increase the protection of coastal wetland areas that these birds rely on.
Darwin Harbour