Don Knowler
The Walker Corporation, when it first proposed its Ralphs Bay development, said shorebirds displaced by the dredging and land-filling for the marina and its infrastructure would find a home in areas that the developer was rehabilitating and conserving. This appears to be a simplistic view, as the research by Birds Tasmania and its affiliate national organisation, Birds Australia, demonstrates. If there is one constant in declining bird populations, it is that when birds are forced out of any natural habitat — be it forest, desert or seashore — overall numbers suffer a drop.
Ralphs Bay is, in fact, home to some of the biggest populations of shorebirds found in the state. It is especially noted for its vast population of pied oystercatchers, with an estimated 5 per cent of the total world population making a home there. With such large numbers of not only oystercatchers but other resident waders, virtually every square metre of mudflat is already claimed by birds for nesting, roosting and feeding.
Here I write only of our resident shorebirds and do not mention the thousands of waders that come to Lauderdale and other mudflats on Tasmanian coasts from their breeding grounds in the northern hemisphere during our summer.
WE birdwatchers are a twitchy lot when it comes to people encroaching on our space, or should I say birds’ space.
We’re not really anti-development and progress, just a little protective of Mother Nature.
The ongoing debate about forestry in Tasmania and concern about coastal development has raised an interesting point about where our birds — and mammals, reptiles and amphibians — go when their habitat is taken away from them.
The proponents of the Lauderdale Quay marina development have stated that much of the mudflats in Ralphs Bay will still be protected, so shorebirds displaced by the 500-house development will merely move to new areas.
And from statements that Forestry Tasmania and other forestry organisations make about regrowth forest, there seems to be a perception that birds will simply fly from forests during felling operations and return once trees have begun to grow again.
In truth, as Birds Tasmania has shown time and time again in more than 30 years of monitoring avian populations, individual birds and sometimes whole communities simply fade away when they lose their territories.
When it comes to waterside development, the pied oystercatcher is a case in point. Once common on the mudflats and sand bars of New South Wales, this elegant wading species has now been listed as vulnerable in that state. Its decline has been attributed to increased coastal development for an expanding NSW human population and resultant increased beach use.
It is a sad fact that the oystercatcher favours a coastal habitat of estuary and beach which is also at a premium for people.
The Walker Corporation, when it first proposed its Ralphs Bay development, said shorebirds displaced by the dredging and land-filling for the marina and its infrastructure would find a home in areas that the developer was rehabilitating and conserving. This appears to be a simplistic view, as the research by Birds Tasmania and its affiliate national organisation, Birds Australia, demonstrates.
If there is one constant in declining bird populations, it is that when birds are forced out of any natural habitat — be it forest, desert or seashore — overall numbers suffer a drop.
Ralphs Bay is, in fact, home to some of the biggest populations of shorebirds found in the state. It is especially noted for its vast population of pied oystercatchers, with an estimated 5 per cent of the total world population making a home there.
An alarming decrease
With such large numbers of not only oystercatchers but other resident waders, virtually every square metre of mudflat is already claimed by birds for nesting, roosting and feeding.
Here I write only of our resident shorebirds and do not mention the thousands of waders that come to Lauderdale and other mudflats on Tasmanian coasts from their breeding grounds in the northern hemisphere during our summer.
In forests, similar principles apply to territories. A mature old-growth forest is a diverse environment that not only offers a range of food for birds but nesting sites, especially in old trees. A regrowth forest cannot possibly provide homes for cavity-nesting birds, to say nothing of Tasmania’s eight species of bat and other tree-nesting mammals.
It takes many years, sometimes in excess of a century, for suitable nesting cavities to develop in some gum trees.
An alarming decrease in some forest and woodland bird species has been noted in Tasmania in recent years, particularly in our robins. A population census of our four robin species, plus numbers of the swift parrot, is being carried out by researcher Sarah Lloyd and in Birds Tasmania’s Yellowthroat newsletter she made the point that when an area of land, however small, was cleared, birds simply vanished and died.
Her observations tie in with the findings of the wider Atlas of Australian Birds compiled by Birds Australia, in which it has been established that the diversity of bird species is declining while, at the same time, common birds are becoming more common.
It means birds dependent on one habitat — such as swift parrots, largely relying on blue gums in summer — will die out eventually, to be replaced by smaller numbers of species that can better use an environment reshaped by man.
In plantation forests and on farmland, noisy miners and introduced starlings will dominate. On the waterfront, all we’ll see in future are masked lapwings, silver gulls and white-faced herons.
Don Knowler’s article first appeared as the “On the Wing” column in Saturday’s Mercury
