Careful surveillance and testing are crucial to confirming whether bird flu cases in migratory seabirds are isolated events or part of a broader pattern, experts say.

Scientists have urged the public not to panic after H5N1 bird flu was detected in preliminary testing of a migratory bird at Hawks Nest, on the NSW Mid-North Coast, on Friday.

Five cases of the strain have been confirmed in seabirds in Western Australia and South Australia, along with another suspected case detected on Friday in a migratory bird in the northern Perth suburb of Mullaloo.

The suspected NSW detection was significant and should be taken seriously but was not a reason for panic, Burnet Institute scientific director for research translation Heidi Drummer said.

"The risk to the general public remains low," Professor Drummer said.

"Avian influenza viruses do not easily infect people, and human infections usually occur after close contact with infected birds, infected animals or heavily contaminated environments."

Prof Drummer said careful surveillance and testing were crucial as authorities tried to determine whether the detections in migratory seabirds were isolated events or part of a broader pattern of virus movement in wild bird populations.

"It is important to be clear that detection in wild birds does not mean the virus is widespread in Australia, or that it has entered commercial poultry," she said.

"Detecting the virus early gives authorities the best chance to understand where it is, limit spread where possible, and protect poultry, wildlife and people."

The strain was first detected on the Australian mainland on June 14 in a brown skua found in Esperance, on WA's south coast.

More substantial testing is expected to confirm the NSW case at the weekend.

Emma Grant, from La Trobe University's Institute for Molecular Science, said the virus could spread very quickly.

"It can also be quite severe in different animals, so what it means for the wildlife in Australia is yet to be seen," Dr Grant said.

"That's certainly been the talk from a lot of experts in the field, that we don't know what is going to happen to our native bird populations."

The public has been urged to avoid contact with sick or dead wildlife, report any finds to an emergency hotline, record locations and take photos.

The spread among migratory birds was "largely inevitable" but Australia was still doing "a very good job" of containing bird flu, Mater Health Services director of infectious diseases Paul Griffin said.

"While we are talking about three states and still a very small number of cases, it highlights how we have to remain vigilant and make sure that we protect the poultry industry and other bird populations," Professor Griffin said.

All positive cases had occurred in wild birds, with no signs the virus had spread to local poultry populations.

It was now "only a matter of time" before further cases were detected in other states, and the impact on commercial bird populations could be devastating if large-scale culls were required, Prof Griffin said.

"But we do have good protocols in place … some of the largest producers have implemented more stringent measures to reduce that risk," he said.