BIRDWATCHERS gathered on wetlands across Australia earlier this month for a “farewell to shorebirds” celebration to send the migratory waders on their way to breeding grounds on the other side of the world.
But in truth there was not much to celebrate. Shorebird numbers are in freefall because of the draining and degradation of the wetlands in which they live over their whole migratory range, which stretches from the far south of Tasmania to breeding grounds within the Arctic Circle.
The population figures for just three species that come to Tasmania along the East Asian Australasian Flyway tells the story.
Numbers of curlew sandpipers – a mid-sized wader with a long, curved black bill – are down 85 per cent, and are decreasing by 8 per cent a year. The biggest shorebird in the world, the eastern curlew, has seen a population loss of 50 per cent since it was once hunted for the pot in the marshlands of Pitt Water and Orielton Lagoon at Sorell. And the smallest wader to come to Tasmania, the red-necked stint, is down by a third. The stints, the size of sparrows, live for 20 years which means they will fly the distance to the moon during their lifetimes.
Vanishing shorebirds have become what scientists term “coastal canaries” for sea-level rise and the degradation of wetlands and coastal areas.
In the way canaries were once used in coalmines to alert miners to the presence of life-threatening methane gas – canaries were more susceptible to gas poisoning – shorebirds are now sounding the alarm about our vanishing coastline.
Birds have long been a barometer for damage being caused to the environment by human activity. The collapse of bird of prey populations in the 1950s alerted governments to the threat certain man-made pesticides like DDT posed to humans, and in more recent times the discovery of hundreds of dead parrots in a West Australian port revealed dangerous concentrations of air-borne lead, being loaded for export. Now shorebirds are revealing that all is not well with our coastal and wetland environments.
“Shorebird and seabirds are sensitive indicators of the state of the health of Tasmania’s coastline, and the many long-term surveys and monitoring by BirdLife Tasmania over many decades show decreases in abundance and species diversity of birds on our beaches and coasts,” said BirdLife Tasmania convenor Dr Eric Woehler.
Although the visitors from the northern hemisphere nest in tundra rather than on coastlines, vanishing wetlands on their migratory journeys through South-East Asia, and here in Australia, are denying them the chance to feed on route.
Resident beach-nesting species such as the hooded plover also face the prospect of losing their nesting habitat in Tasmania.
The development and construction of coastal infrastructure such as roads and houses will stop the inward migration of the coastline, says Dr Woehler. “So, as the sea level rises, essentially what you are going to end up with is a sea wall rather than the capacity for the coastline to find its new location or extent inland of where it is now.”
The crisis facing shorebirds is one that, ultimately, will also affect humans living near the coast.
Dr Woehler says that sea-level rise is a scientific fact. As far as birds are concerned, vanishing wetlands and beaches affects both migratory and resident shorebirds. Resident species, however, also have to contend with pressure on their beach-nesting sites from increased human recreational activity along our coasts.
Beaches are proving increasingly popular with dog-walkers, horse riders and four-wheel drive enthusiasts.
BirdLife Tasmania has long campaigned for important breeding beaches to be declared no-go zones for dogs, horses and four-wheel-drive vehicles during the summer months when birds are nesting on beaches.