First H5N1 bird flu case detected in an Australian dolphin

A dead dolphin found at Goolwa on South Australia's Fleurieu Peninsula has returned a positive test result for H5N1 bird flu, according to state authorities.

SA's Department of Primary Industries and Regions (PIRSA) said the detection in dolphins was a "new development in Australia", though several cases have been reported in other countries.

The state's chief veterinary officer Dr Skye Fruean said it was expected the dolphin had "eaten a bird or interacted closely with a wild bird".

"We know that dolphins are highly susceptible, which means they are at risk," she said.

Dr Fruean said there were few reports globally because infected dolphins were rarely found on shorelines.

The detection followed a positive result in a red fox found in Adelaide's north-west earlier this week.

More than 350 positive bird flu events have been reported in Australia, with South Australia sitting at a total of 249 following the confirmation of 46 overnight.

PIRSA said the larger-than-usual number of confirmed events overnight was due to a new provision allowing the state to consider its positive detections as official without additional verification by the CSIRO's national lab in Geelong, as was previously the case.

Dr Fruean said that it would mean detections would be confirmed sooner.

"We've been conducting that testing here at our lab in Adelaide, in parallel to the testing that has been happening at ACDP, which means we're both testing the same samples and we're consistently getting the same results," she said.

"That national lab is really there to be doing the more complex cases where we can't be sure of own results, or they need to do the more detailed analysis."

So far, most events have been concentrated on Australian coastlines, but detections are expected to increase as the virus circulates between bird and animal populations.

The Australian Antarctic Division is preparing to extract its researchers from Macquarie Island to avoid psychological risks posed by potential mass wildlife deaths on the continent.