BIRD MIGRATION – Part 2 Shorebirds (aka Waders)

In the last Volunteers Voice issue (December 2022), I discussed why birds migrate and types of migration. Now I’ll discuss more of the remarkable shorebirds, some of which fly incredible 25,000km round trips.

They reach Australia in our spring, in transitional (partial breeding) plumage from their Arctic Circle breeding grounds. For them, Australia is a non-breeding (Rest and Recreation - R&R) region in which they avoid the long, mind-numbingly cold Northern Hemisphere winter and its lack of food.

While here, they undergo their annual flight feathers moult (October-February), which is essential to ensure they’re in top condition for their coming arduous return flight to their Arctic breeding grounds. To gain energy for these grueling flights, they eat high-fat prey such as molluscs, crustaceans, marine worms and insects during their southern R&R. If eating plant matter, they prefer high fat seeds and fruits.

Between the Arctic and Australia most follow the western Pacific’s East Asian-Australasian Flyway (EAAF) along Asia’s coast and islands (some 8,000-12,500kms each way). This involves very long flights and rest stops in a chain of staging posts, so they can ‘refuel’ for the next leg of their journey. The coastline is much safer than crossing the ocean as shorebirds rarely swim, and if they fell into the ocean they would probably drown.

Along the EAAF, environmental degradation of the birds’ rest stop staging areas by onshore development (eg fish farms, land reclamation, housing, pollution), has resulted in tragic loss of birds. Some areas that supported many thousands of shorebirds 30 to 40 years ago, no longer do so: many sites no longer exist or are severely damaged, and birds can’t refuel enough to continue their journey. Many weaken and starve to death, or drown en route. Refuelling is crucial. The resulting overall decline in shorebird populations over the past 30 or so years is a disaster for Earth’s diversity, environmental health and future.

Many international birders visit Cairns, the Atherton Tablelands and Cape York, often during summer, for the shorebirds. Here are four shorebirds that bring visitors.

Pacific Golden Plover (Pluvialis fulva) arrives in Australia in September/October from northern Siberia. It follows the EAAF to India, southeast Asia, Australia, New Zealand and Oceania for our southern summer. When their stunning (black, and speckled cream and gold) breeding plumage starts to develop (as pictured) they start their northern migration.

In Australia, they prefer estuaries, tidal flats, beaches and reefs, especially with seaweed, salt-marshes and rocky coasts. They run in the typical plover stop-start sewing machine-style to catch small molluscs and crustaceans.

Bar-tailed Godwit (Limosa lapponica) arrives in Australia in September/ October from north-eastern Siberia and western Alaska. Its southern journey is a non-stop flight of about 10,000km (the longest non-stop flight known for any bird) directly across the Pacific Ocean to eastern Australia and New Zealand. On its return trip it follows the EAAF refueling at staging posts en route.

In Australia they prefer large tidal flats, feeding on molluscs, crustaceans and marine worms found by repeated shallow probing with their long sensitive bills. They leave in April/May to return to their Northern Hemisphere breeding grounds.