Bird‑generated power

Australian Geographic.
Oct-Dec 2006, No 84

Where have all the orange‑bellied parrots gone?

WHAT'S 22 cm long, weighs just 50g and has the power to block a proposed wind farm development? With just 150 or so of its kind left, it's Australia's Orange-Bellied Parrots (OBP).

This little bird is about as close to extinction as you can get without actually vanishing. And in April, its precarious state gave the Federal Government a reason to knock back a proposal for a wind farm in South Gippsland, Victoria. The project was destined for a site near the parrot's coastal migration route. It would have been just one more development ‑ on top of houses, industrial complexes and farms ‑ that has made much of the OBP's mainland winter habitat inhospitable.

But not everyone agrees that this particular wind farm was a problem. Chris Tzaros of Birds Australia says: "That wind farm wasn't a danger to OBPs, but there are other sites that are right on the migratory route. It's not just wind farms though; it's all sorts of industrial development going on all the time that is potentially threatening." Further, bird‑lovers are worried about a mysterious drop in the number of Orange-Bellied Parrots turning up at some of their traditional wintering grounds since the early 1990s.

It's a paradox, since the parrot's total population hasn't fallen in the same period; ornithologists know this because the number returning to their summer breeding areas has been about the same every year. So where are the birds hanging out in winter? Until about 1992, bird spotters were counting up to 90 birds in the OBP's winter habitat of southern Victoria and south‑east SA. "Since then they've really dropped off and we're just not finding the numbers we used to," says Chris.

Chris is coordinating a three‑year project, funded by the Federal Government's Natural Heritage Trust, that hopes to pinpoint the kind of habitat OBPs prefer. Once this is known, the habitat can be protected ‑ if it isn't already ‑ so that the species' toehold on the planet can be made a little less precarious. The information may also lead ornithologists to OBP habitat they're not checking at the moment.

"It's too early to say much about habitat preferences other than what we already know ‑ that they prefer salt marsh close to water on complex coastlines," Chris says. "It might turn out that they're using what we know is the right habitat but in a completely different area that no‑one's researching." OBPs spend the summer in Tasmania's south‑west, feeding on seeds and fruit in button grass plains and roosting in copses of paperbark and tea‑tree. They breed between November and February, each female laying 4‑5 eggs in eucalypt hollows. Once the chicks have fledged, adults set off across Bass Strait, via King Island, to their winter habitat on the mainland coast. Youngsters follow a month or two later. On reaching the mainland, the birds radiate out from South Gippsland to the south‑eastern corner of SA, although 70 per cent stick around the western rim of Port Phillip.

At the time of European colonisation, the OBP used to range as far west as SA's Yorke Peninsula and east to Sydney. In Tasmania, early colonists reported seeing them on the island's east, around Hobart. In 1836, 1886 and 1918, the parrots were recorded in their thousands, and as late as the 1920s they were still common and locally abundant.

But after that the species went into a steep decline. The main cause was coastal development, cat and fox predation, and exotic seed‑eating birds such as sparrows and finches competing with them for food. These days a patchwork of reserves helps protect their remaining breeding and wintering habitats.