Perfect mix: stage set for 'maximum' bird flu damage

A mass cluster of deadly bird flu cases has increased the likelihood of the virus spreading inland. (Richard Wainwright/AAP PHOTOS)

An escalating bird flu outbreak is poised to cause "maximum damage" following confirmation of Australia's first mass mortality event.

The mass mortality event was confirmed on Monday after a large group of dead and sick greater crested terns at Baudin Rocks, in South Australia, tested positive for the virus.