From the coasts to the plains, bird flu could threaten not just birds—but their homes

This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Yesterday, I woke to a cold, damp Canberra morning—and silence. The trees around my home were empty of feathered silhouettes.

Even the usual bright-eyed, warble-voiced magpies were absent. The next morning, they were back. I don't know why they went AWOL.

But their absence felt like a taste of what might come as the lethal H5N1 strain of bird flu spreads in Australia, affecting both birds and mammals. Conservationists once asked, "What is a bird without a tree to nest in?" This year, we may well wonder the grim inverse: What is a tree without a bird to nest in it? A tree without a bird is a miserable thing—and in a broader ecological sense, a tree without a bird could be in trouble.

In Australia, birds act in many roles that mammals or insects might fill elsewhere, from pollinating flowers to spreading seeds to keeping trees free of sap-sucking insects. Bird flu doesn't just threaten birds and mammals—it could well affect entire ecosystems. Australia's birds play vital roles in most ecosystems.

As honeyeaters squabble in the canopy, mound-builders such as orange-footed scrubfowls and Australian brush-turkeys turn over vast volumes of soil and leaf litter on the forest floor as they look for bugs or make their giant mounds. Their digging loosens and aerates the soil, giving seeds a better chance of germinating and encouraging leaf litter to break down. In more open woodlands and shrublands, this work is done by birds such as malleefowl, quail-thrushes and babblers.

In Australia's wetlands, plant-eating waterbirds such as black swans and whistling ducks disperse seeds and help balance plant growth, while insect eaters such as musk ducks do the same for aquatic invertebrates. As foraging herons and pink-eared ducks stir up mud at the bottom to flush out insects, they boost oxygen levels and circulate nutrients. As seabirds and shorebirds move between coral reefs, mudflats, islands and oceans, they deposit nutrients.