Migratory Shorebirds
ROEBUCK BAY lies near the town of Broome on the shores of north-western Australia and has long been recognized as an internationally important place for migratory shorebirds (waders) that come to feed on the invertebrates in the extensive mudflats. These small to medium-sized birds (sandpipers, plovers and allies) nest in the northern hemisphere and migrate annually to non-breeding sites such as Roebuck Bay. Australia has ratified a number of international conservations such as the Ramsar Convention and treaties with Japan, China and Republic of Korea and has a legal obligation to protect migratory shorebirds and their habitats.
Roebuck Bay’s mud flats range in texture from fine silts to sandy banks and provide a home for an amazingly wide range of invertebrates which in turn feed at least 29 different species of shorebirds with various bill sizes and shapes and feeding techniques. Marine worms are soft and easy to swallow whilst other prey require specialist skills to eat. A good example of this is the Great Knot which eats bivalves, swallowing them whole and grinding up the shells in a very strong gizzard to extract the soft flesh.
When the tide is high it covers the mudflats meaning the birds cannot feed. They are forced to find sandy bays and rocky outcrops to roost (rest) on until the tide recedes once again exposing the rich and plentiful food supply.
Disturbing roosts threatens shorebirds
THE ROOST SITES in Roebuck bay are very important as they have been identified as the only daylight roosting option available for shorebirds in the north of the bay. While the birds are roosting they are very prone to disturbance from birds of prey such as the Brahminy Kite and human influences such as driving on the beach and uncontrolled dogs.
Shorebird migration range on the East Asian-Australasian Flyway. Press to enlarge.
Shorebird migration range on the East Asian-Australasian Flyway. Press to enlarge.
If high levels of disturbance are experienced by shorebirds at their roost sites it can have a bad effect on their welfare. The danger that birds face is how to accumulate fat that they need to moult and grow new feathers and more importantly to make the huge migration to areas such as the Yellow Sea in China some 6000 km away. They need to increase their body weight by some 55 – 85 % and will use the stored fat to fuel their flight to the next rich food supply – the Yellow Sea – where they will again refuel for their flight to the breeding grounds in the Arctic and sub-Arctic regions. If the birds are constantly disturbed at high tide roosts they use up precious fat reserves which reduce the chances of successful migration. If they cannot make the journey there will be no chicks produced and over time the population will dwindle and decline.
Research, education & conservation
Chris Hassell with an Endangered Asian Dowitcher. © 2008 Chris Hassell. Press to enlarge.
THE BROOME BIRD OBSERVATORY was established to work for the conservation of migratory shorebirds which visit Roebuck Bay along with the many endemic birds of Broome. The Observatory is involved in International shorebirds migration research and was recently involved in fitting satellite transmitters to twelve Bar-tailed Godwits. They departed in April for the Yellow Sea, spending approximately 6 weeks there feeding up before departing for their breeding grounds in Siberia. The journey was followed back to Roebuck bay when they arrived in September/October.
Migratory Shorebird study results released
Read Chris Hassell’s latest report on his work with the Global Flyway Network on Migratory Shorebirds in Bohai Bay, Northern China during April May 2010. The GFN report of the field work in Bohai Bay, Northern China during April and May 2010 is now up on the Global Flyway Network site.
Peak scientific publication to use data from GFN study
There will also be a scientific paper published in the next volume of “Emu-Austral Ornithology” using the data from Chris Hassell’s 2009 visit and the data from Yan Hong Yan. This report highlights the pressures that the migratory birds are facing during their stopover periods in the Yellow Sea. It is rather depressing reading (but interesting I hope!) If you go to the front page of the website there is a blue box on the left hand side and it is the bottom item in there or open the report here »
How can you help to support these birds?
The answer is simple, when you visit the bay, please:
- watch the birds from the tops of the cliffs
- avoid walking through flocks of roosting birds
- keep your dog on a leash, and
- do not drive on the beach.
A Bar-tailed Godwit in breeding plumage. © 2004 Adrian Boyle. Press to enlarge.
Ideally situated on the shores of Roebuck Bay, Broome Bird Observatory (Birds Australia) has unequalled access to the hundreds of thousands of migratory shorebirds which visit the region. Visitors learn the amazing story of these birds and witness some of the great sights in nature: the vast roosting flocks on beautiful beaches during high tide; thousands foraging on the mudflats as the tide falls; stunning breeding plumage among massive pre-migratory flocks in March, and; their breathtaking departures for Asia, as they begin their migration in March/April each year. In addition to accommodating tourists and nature enthusiasts, the Observatory offers a base from which scientists, researchers and students have easy access to the bay.
If you wish to visit the bay please contact the Observatory staff to find out the best way to view the birds.
P. +61 8 9193 5600 (international)
P. 08 9193 5600 (within Australia)
bbo@birdsaustralia.com.au