What would happen if bird flu made it into the australian bird population?

Answer 1

The likelihood of the disease spreading to humans will increase there. See
http://www.smartraveller.gov.au/zw-cgi/view/TravelBulletins/Health_%3A_Avian_Influenza

Answer 2

In addition of Australia's problems, the whole world would go into mass hysteria and the WHO (World Health Organization) would spring into action to try to prevent further spread.