The Albanese government has called for calm over fears a deadly avian flu strain is spreading in the country's biggest state, with 16 birds dying or becoming sick.

The H5N1 variant of the virus was confirmed in a sick brown skua found on a remote beach near Esperance in Western Australia, about 700km south-east of Perth.

A second migratory bird, a giant petrel, has also returned a preliminary positive result, but further investigation is needed.

Environment Minister Murray Watt said while the federal government was aware of numerous reports of sick and dead birds, it wasn't clear whether they related to bird flu, or the 'many other reasons birds die every single day'. 

'At this point, there's no need for alarm that this has become a more widespread incident beyond those two birds,' Mr Watt told ABC Radio on Monday. 

He said if Australia was to have a widespread outbreak, it would have a very significant impact on native wildlife, rather than poultry stocks. 

'We know that bird flu can not only impact on birds but also mammals as well... the ones that we're most concerned about are our most endangered species, whether it be particular types of birds, [and] the Australian sea lion.' 

The strain was previously detected on Heard Island in October, where an estimated 13,359 southern elephant seal pups died.

Australia has been preparing for the arrival of H5N1 for years as the only continent yet to be impacted by the strain.

The federal government has developed more than 100 response plans for key sites and vulnerable species and invested about $100 million in preparedness. 

The discovery has fuelled fears among scientists, conservationists and agricultural groups, who point to mass mortality events and species-level population reductions in overseas outbreaks.

University of Melbourne researcher Michelle Wille said Australian authorities had been preparing for a worst-case scenario, but international examples painted a gloomy picture. 

'Everywhere this virus has emerged has been really catastrophic, with mass mortality events in wildlife, and in some places, we've seen species-level reductions in population,' she said.

Industry impacts could also be significant, she said, noting more than 200 million chickens had been culled in the United States since the virus arrived there.

The public has been urged to avoid, but report and record sick and dead birds and marine mammals to the emergency animal disease hotline.