The deadly bird flu virus has spread to native birds in another state, as the national tally continues its steep rise across the country.Two greater crested terns returned positive for the H5 flu strain in NSW, with one found near Narooma on the state's south coast and the other near Wentworth close to Mildura, officials confirmed on Saturday.There have now been 215 confirmed or presumed positive detections, although the poultry industry remains clear of the virus so far.It's the first time that avian influenza has been detected in an Australian native bird in NSW, with the state now recording four cases."These positive cases are not unexpected We have been preparing for a situation like this, and we remain well equipped to respond to manage further impacts," Environment Minister Penny Sharpe said.Surveillance in the impacted areas is continuing to ensure early detection of any further cases, the government added.Testing at CSIRO's Australian Centre for Disease Preparedness confirmed on Saturday a further 10 detections of bird flu, all from greater crested terns in Victoria's southwest and Melbourne.There were 28 positive detections in South Australia among wild seabirds, mostly among greater crested terns, with 15 of those on the state's Limestone Coast and 11 on Kangaroo Island, Australia's Chief Veterinary Officer Beth Cookson said.SA chief vet Skye Fruean said there was no particular reason why the state had so far encountered most of Australia's confirmed cases."Unfortunately, we were just unlucky to be the first place where this did spread into our resident birds," she told ABC."I expect there will be other spread in other states and territories with time but ..