A dramatic if tragic portrayal of the epic migrations made by shorebirds is highlighted in a documentary Flyways which has been showing in cinemas across the country.
The most poignant scene for me when I saw the film in Hobart last month was the sight of birds popularly known as waders probing and wading amid piles of plastic rubbish on a sandspit along their migration route in China.
Plastic pollution, hunting and the reclamation of wetlands are the main threats to both migratory and non-migratory shorebirds.
Ironically, the flotsam and jetsam of the human world actually aids another group of birds – the gulls – and they are increasing in number in urban areas.
This stark contrast between the plight of the shorebirds and the gulls struck me a few weeks after seeing Flyways when I signed up for the annual survey of the three gull species found in Tasmania, the silver, kelp and Pacific gulls.
Unlike the waders which inhabit often difficult to reach marshland and mudflat, bird-watchers conducting gull surveys do not have to travel far to find them. The gulls are all around Hobart, at fast-food outlets, fish punts on the docks and, especially, on the city’s rubbish tip.
Forty years of surveys continue to confirm our gulls are not under threat despite the health hazards of feeding on fish and chips, discarded hamburgers and hot dogs. The urban gulls are far from healthy, however.
Comparison of silver gull populations on Bass Strait islands with those in Hobart have found that, like humans on a fast-food diet, the gulls are overweight and have higher cholesterol levels, thus being prone to diabetes and heart attack.
The gulls are not alone among birds in exploiting the rick pickings of the city.
In mainland cities a bird not found in Tasmania – the white ibis – is known as the “bin chicken” and the art of raiding bins has also been perfected by the sulphur-crested cockatoo, which in Sydney has even learned to pick the locks of devices designed to keep the bin lids shut.
It is not only the birds that feed on the garbage produced in our cities that are flourishing. Another parrot, the rainbow lorikeet, is booming in number because it has discovered that the suburbs are rich in exotic vegetation which provides an abundance of pollen and nectar, and fruit and nuts, all year round, thus boosting population numbers.
The abundance of city birds, though, obscures the fact that away from the cities numbers are in freefall. Hardest hit are the specialist, niche species that thrive in specific environments.
Out of Australia’s more than 800 bird species, the ones that have discovered the lucky country within our cities are in the vast minority, perhaps only 20 species.
Country-wide, about a quarter of bird species are threatened with extinction, with waders topping the list.