filed Jan 10.2007
The unexplained near-extinction of birds around the town of Esperance mirrors a similarly mysterious sudden mass aviary death in the US.
Reports of birds dropping dead in people's yards around Esperance, on the southern coast of Western Australia, began to come in three weeks ago, well before last week's freak storm that caused devastating floods in the region.
The reports stopped this week as the skies became clear of birdlife.
The main casualties are wattle birds, yellow-throated miners, new holland honeyeaters and singing honeyeaters, although some dead crows, hawks and pigeons have also been found.
The WA Department of Food and Agriculture has conducted autopsies on five birds and believes ingested toxin is the most likely cause of the deaths, but has not pinpointed a culprit among hundreds of possible poisons.
Authorities are asking people to bring more birds in the hope one may have enough food in its stomach to identify a common deadly toxin.
"It doesn't appear to be an infectious cause. Certainly, one thing that is being considered is a toxin," acting chief veterinary officer Fiona Sunderman said.
Dr Sunderman said the investigation had been hampered because the dead birds had very little in their stomachs, suggesting the food had been regurgitated or the birds were so unwell they could not eat.
Any one of hundreds of toxins could be causing the deaths but so far all leads had been dead ends, Mr Fitzgerald said.
"We're dealing with birds that eat insects and nectar, so we're at a loss to understand how the toxins have actually entered their food web," he said.
"Lead and arsenic and several other heavy metal materials are sometimes shipped through Esperance, but that doesn't seem likely."
Tests have also ruled out the toxin being introduced through insects.
"The birds are dying around sprinklers, water tanks, bird baths ... it seems as a result of them being ill. They're seeking water and they're dying around those water points," Department of Environment and Conservation (DEC) district nature conservation co-ordinator Mike Fitzgerald said.
"We need to identify what toxin it is or we need to find the toxin in the water ... something to point where to take this," Mr Fitzgerald said.
Esperance bird watcher Alan Rose said he had never seen anything like it and was concerned it could spread to the local population of Cape Baron geese and push it to the brink of extinction.
"Numbers are not large, so they are vulnerable," Mr Rose, a member of bird watching group Birds Australia WA, said.
On Sunday the central business district of Austin, Texas in the US was partly shut down on after dozens of birds were found dead in the streets, wire service AP reported.
As many as 60 dead pigeons, sparrows and grackles were found with authorities unable to determine what caused the deaths after tests determined their was no poison in the air.
Experts said the most likely cause was a deliberate poisoning of the grackles, widley regarded as pests.
Officials however were continuing investigations because as one said, the birds' "requirements for life are pretty similar to our requirements for life" so they can serve as an early warning for risks to human health."
(Original headline: Mass bird death mirrors US )
