Extinct Australian birds increase by 25%
ONE SPECIES AND FIVE sub-species of Australian birds that, when last surveyed ten years ago, were listed as critically endangered, are now thought to have been extinct for many years.
This means a 25 per cent increase in the number of extinct Australian birds, with the likely culprits being habitat loss, interbreeding and introduced predators, says environmental scientist Professor Stephen Garnett of Charles Darwin University, NT, the co-author of a new study.
Australia’s Environment Protection and Biodiversity Conservation Act has up until now listed 23 species and subspecies of birds as extinct.
Going, going, gone
The missing birds include the white-chested white-eye (Zosterops albogularis) from Norfolk Island, last spotted in the 1980s. This species is thought to have been driven to extinction by rats which invaded the island after World War II and ate the bird’s eggs.
The other sub-species of birds now thought to be long extinct are: a pied currawong (Strepera graculina ashbyi) from Victoria’s Grampians National Park; a thick-billed grasswren (Strepera graculina ashbyi) from Alice Springs; South Australia’s spotted quail thrush (Cinclosoma punctatum anachoreta); the eastern coast’s southern star finch (Neochmia ruficauda ruficaud); and the Tiwi Island’s hooded robin (Melanodryas cucullata melvillensis).
“We were worried about these birds when we last reviewed their status 10 years ago,” Stephen said. “Sadly, no sign of them has turned up in the past decade.”
The study was released this week by conservation groups including Birds Australia, BirdLife International and the Australian Wildlife Conservancy. One major conclusion is that these species could have been protected at little expense if the problem had been realised early enough. “If we had been more aware [of the threat] 30 years ago, some of these birds could have been saved,” says Stephen.
Two of the five sub-species have not been seen in the wild since the early 20th century, but the Tiwi Islands’ hooded robin was spotted as recently as 1992. It has declined because islanders moved to settlements, and stopped burning the land as they had done traditionally, meaning less open habitat for it to feed in.
Its southern relative is now also under threat. “The hooded robin is furiously declining from the wheat belt woodlands in New South Wales and Victoria, because of agricultural clearing,” says zoologist Dr Stephen Debus of the University of New England in Armidale, NSW. “Its key habitat elements like native tussock grasses, standing dead trees, logs and coarse woody debris are all the sorts of things that farmers like to get rid of.”
While Stephen concedes that the loss of the five subspecies is “lamentable,” he argues there are greater threats for us to be concerned about. “These sub-species mostly belong to widespread species which still exist,” he says. “There are other whole species which are critically endangered.”
One of these is the migratory orange-bellied parrot (Neophema chrysogaster), which has lost much of its winter habitat along the coast of South Australia. It’s unlikely to survive for much more than a decade, Stephen says, as just 50 remain in the wild today.
“This [study] just more evidence of how badly we have damaged the Australian environment since European settlement,” says co-author Professor Hugh Possingham of the University of Queensland. “We have extracted enormous economic wealth from Australia, a far greater proportion of the dividend must be invested in biodiversity conservation if we are to stem the loss of our wildlife.”