Is it an illness, toxins or a natural phenomenon? A string of autopsies in Perth have shed no light on the mystery.
All the residents of flood-devastated Esperance know is that their "dawn chorus" of singing birds is missing.
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, which the Department of Environment and Conservation said began well before last week's freak storm.
On Monday, Esperance, 725km southeast of Perth, was declared a natural disaster zone
AUSTIN — The mysterious deaths of more than 60 grackles, sparrows and pigeons that touched off a dramatic shutdown of a dozen streets along Congress Avenue ended in a cliffhanger Monday, with officials still uncertain about what killed the birds.