What happens next with bird flu? An expert explains why monitoring matters

As the H5N1 strain of avian influenza rapidly spreads along the southern Australian coast, killing thousands of wild birds and infecting at least two seals, the question arises: where will it travel next and what damage might it inflict? While much remains uncertain, particularly given the unique nature of Australia's animals and ecosystems, monitoring the outbreak is crucial to understanding its magnitude and protecting vulnerable species.

Australia's bird flu crisis may unfold in several ways. Waterfowl, such as ducks, herons, and swans, carrying the virus, will likely spread it inland to wetland systems. The timing is concerning, as El Niño climate patterns will create hot, dry conditions, shrinking wetlands and forcing waterfowl to congregate at scarce water sources. This high-density congregation could lead to further virus-contaminated losses.

While Macquarie Island's seabird, seal, and king penguin colonies have so far avoided the virus, it will soon spread to the densely packed penguin, seal, and petrel colonies. Government efforts to evacuate researchers from the island aim to protect their well-being. Vast flocks of shearwaters, returning from their global migration, will nest on islands off southern Australia and may face substantial losses from the virus.

Scavengers, including foxes, cats, and mynahs, will carry the virus to urban areas, potentially impacting urban wildlife like magpies and possums.

But hope exists. While bird flu has not yet caused any extinctions worldwide, some species have shown signs of recovery after initial outbreaks. The challenge now is to assess the conservation impacts of H5N1 on Australian wildlife. While dead bird counts provide some information, they do not fully capture the conservation impact. Focusing on the proportion of a species' total population killed by bird flu will better assess consequences and recovery potential.

However, assessing population-level impacts may be difficult due to limited population data for many Australian species, particularly vulnerable ones like colonial-breeding seabirds and seals. Monitoring programs, like aerial surveys of waterfowl, could yield critical data. Yet, statistical "noise" and monitoring biases may complicate identifying population declines caused by bird flu.

To truly understand the nuanced impacts of H5N1, monitoring should evaluate the effectiveness of management actions, changes in breeding success, immunity levels, mutations, and virulence of the virus. Additionally, it should investigate survival rates of infected individuals, broader environmental risks, and potential recovery. Without robust monitoring, the true magnitude and significance of this outbreak cannot be grasped, hindering targeted emergency responses and measuring the success of our actions.