Clue to ‘silent summer’ in Esperance

In a sort of grim nod to Rachel Carson’s Silent Spring, the birds of Esperance, Western Australia, have been dropping out of the sky in their thousands since December — “and no one knows why.”

Locals were dismayed to find that their “dawn chorus” had disappeared.

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. Wildlife officers are baffled by the “catastrophic” event...

Dr [Fiona] Sunderman [of the WA Department of Agriculture and Food] said there were no leads yet on which of potentially hundreds of toxins might be responsible. Some birds were seen convulsing as they died.

• The Australian, 10 January 2007

Speculation about unknown toxins in the environment around Esperance led to concerns for public health — but evidently not to the extent of a similar and concurrent event in Austin, Texas, where “police shut 10 city blocks as workers in hazardous-materials suits tested for contaminants that may have killed grackles, sparrows and pigeons.” (The Australian, 11 January 2007)

Now preliminary findings have led the WA Department of Environment to suspect lead poisoning as the likely cause of the massive die-off. The possible source of the contamination may even have been identified.

Department of Environment spokesman David Mell said there was still no direct evidence of a lead source, although lead carbonate transported into Esperance for shipping through the port is the main suspect.

The department has already ordered an upgrade of the Esperance Port Authority's air-quality monitoring after lead particles were identified in dust at some monitoring stations.

• The Australian, 10 March 2007

It’s good to be cautious in matters of empirical science, but if I were a resident of Esperance and surrounds, I would be urgently asking about the extent of the problem.

That crows and hawks seem to have fallen victim in this “catastrophic” event suggests that the poisoning may have extended through the foodchain. Where might it end?