More than 400 short-tailed shearwaters have been found dead along the coastline between Esperance and Eucla in the past week, the WA Department of Environment and Conservation (DEC) said.

Seabird deaths also have been reported as far east as Port Lincoln in South Australia.

The DEC said other species, including cormorants, may also have been affected.

In September, a parliamentary inquiry found the export of lead carbonate through Esperance Port contributed to lead pollution which killed almost 10,000 birds.

The latest bird deaths could be "the result of natural phenomena, including migratory stress and algal blooms affecting fish that are subsequently eaten by seabirds'', the department said.

 Several dead shearwaters collected by the environment department have been sent to the WA Animal Health Laboratories for analysis.

The laboratories will examine the samples for toxins as well as bacterial and viral infections. The tests will take about three weeks.

The DEC is in contact with South Australian and Victorian wildlife experts to determine the extent of the latest bird deaths.