THE Cinderellas of the bird world – the migratory shorebirds that usually hide from view in inaccessible and sometimes remote wetlands – are vanishing at an unprecedented rate from the state’s shores.
Two of the species known for their remarkable transcontinental journeys each year from Tasmania to the far northern hemisphere have now been declared “extirpated” in Tasmania and others have seen populations reduced by up to 90 per cent in recent years.
The waders have flown under the radar at a time when there is greater interest in birds than ever. The Australian Bird of the Year contest late last year attracted a record 50,000 entries but not one of the 10 finalists was a member of the prolific wader group. The bird with a winning 11,153 votes was a woodland species, the black-throated finch. The magpie won in 2018.
Although the decline in shorebirds is occurring across all of Australia’s coastlines, it is in southern Tasmania that it is being felt the hardest. Because Tasmania is at the end of the East AsianAustralasian Flyway which links migration routes with northern Russia and Alaska, any fall in bird numbers always shows up first at the extremity of their range.
Although wader experts accept that mortality has always been high among birds that make a perilous 29,000km round-trip each year, current declines are unsustainable. Some waders breed in the Arctic Circle and one species, the bar-tailed godwit, has been recorded flying non-stop up to 11,000km on its southern flight from refuelling stops on the mudflats of the Yellow Sea in China.
The godwit is still to be found on the Sorell and Lauderdale mudflats during our summer but another of the largest waders – the eastern curlew, about the size of a crow with long curved bill – is now difficult to find. It once flew in such numbers that flocks blackened skies over Sorell, where it was hunted for the pot.
Birdlife Tasmania has been monitoring wader numbers for more than 50 years, the oldest data sets in Australia, and these show the curlew is down by 90 per cent in number. It is rapidly approaching the 100 per cent listing for two species Birdlife Tasmania describes as “extirpated” – the once familiar curlew sandpiper and the less common great knot.
Another six waders show drops in number ranging from nearly 90 to 35 per cent.
In all, about 25 wader species visit Tasmania from the north and all show sharp declines although some have been traditionally rare at the furthest point of their range.
Vanishing habitat along the flyway, especially in South-East Asia where mudflats have been drained to make way for industry, agriculture and housing are largely blamed for the wader catastrophe.
But Birdlife Tasmania points out that reclamation schemes that drain wetlands are not just confined to Asian countries. Development along Australia’s eastern coast is also affecting wader numbers, denying shorebirds places to rest and build fat and muscle out of the breeding season, in readiness for the flight north.
The latest statistics were presented to a forum on waders organised by Birdlife Tasmania last month. They are contained in a paper to be published in the journal of the Australasian Wader Study Group, The Stilt.
It has been argued that global wader conservation has been out of Australia’s hands because the main threats to wader habitat have been centred on South-East Asia, especially China. The Chinese government, however, has come to the party in recent years, protecting existing wetlands to aid waders and other waterbirds.
China has been a party to the United Nations-sponsored campaign to save the world’s wetlands – the Ramsar Convention – since joining in 1992 and will host the next Ramsar gathering next year.
The Ramsar agreement is named after the town in Iran where it was drawn up in 1971.
China’s interest in wader conservation is pressuring other nations along the flyway, including Australia, to protect wetland habitat.
This growing recognition of wetlands, however, was not enough to save the vast Saemangeum wetlands of South Korea from a reclamation project completed a few years back, despite protests from international and South Korea environment organisations. The project, encompassing an area of about 400 square kilometres, was one of the biggest reclamation schemes in history and robbed waders of a vital Yellow Sea refuelling stop.
As the paper to run in The Stilt makes clear, conservation remains a global issue and must be viewed across all nations where waders nest, rest or travel.
“While the causes of these decreases at flyway scale may lie primarily outside southeast Tasmania, it is uncertain whether its shorebird habitats remain capable of supporting the peak population levels recorded in the earlier decades of this study,” say the authors.
“This is of concern in the event that the flyway’s migratory shorebird populations recover and predicted changes in climatic conditions that would shift distributions towards the southern limits of their range.” Coastal development is also impacting on the waders that breed in Australia and do not undertake long migratory journeys. These include the pied oystercatcher and hooded plover, birds which for the time being are not as threatened as the international travellers.
Breeding birds are under stress all the same because of vanishing nesting sites and disturbance by increasing numbers of beach users.
The Birdlife Tasmania forum on waders was followed a few days later by a trip to the wetlands of Orielton Lagoon, between Midway Point and Sorell. Whereas thousands of birds might have been spotted in past years, the birders could only spot small parties of one of the smallest waders, red-necked stints. Although only sparrow-size, these still make the arduous journey to the far north each year.
Among the stints were a group of waders that in recent years have become a relative rarity, Pacific golden plovers.
Although out of their striking breeding plumage of jet-black breast and scalloped yellow feathers on the back, these medium-size waders still showed traces of the golden livery that gives them their name. They shimmered in the early morning sun against a backdrop of saltgrass and sparkling lagoon.
Joy at seeing them was tinged, however, with concern that at some stage soon these birds could vanish forever.
Mercury, Hobart, ‘talking point’, February 8, 2020