A dead seabird on a Queensland island has carried H5N1 into a fourth Australian state, completing a slow but steady continental reckoning with a virus that has reshaped wildlife and agriculture across the rest of the world since 2021. Australia's geographic remoteness delayed the inevitable — the mainland held out until June 2026 — yet eighteen confirmed cases across four states now tell the older story: that migratory birds do not observe borders, and that distance is a pause, not a reprieve. Authorities report no poultry infections and low human risk, but the deeper question is not whether t