In the summer of 2022, aboard a small boat in the waters of Dublin Port, a scene from Alfred Hitchcock’s 1963 horror classic The Birds flashed through my mind. In the film, a group of schoolchildren flee in terror as a murder of crows descends upon them, diving and pecking at their heads. Amid the chaos, a young girl stumbles, her glasses shattering on the ground as blood drips from her face.
Admittedly, bobbing along on the boat in Dublin Bay, not a drop of blood was on my face. But as I drifted too close to one of the four concrete nesting colonies of common and Arctic terns, about 150 birds suddenly burst into the air, shrieking and swooping at my hair. For a moment, the attack was genuinely threatening. Swarming into a raucous, synchronised mass over the boat, they moved as one, warning me to back off. It worked.
In the concrete walls and islands of Dublin Bay, nature has found a way to coexist with the relentless, 24-hour human activity, which includes the passage of 8,000 ships each year. In the jetty, guillemots nest in man-made holes along the quay walls, while cormorants and seagulls travel between the land and sea, scanning the waters for food. Halfway up one of the red and white Poolbeg chimneys, a man-made nest box is home to a pair of breeding peregrine falcons. It’s a testament to wildlife’s resilience in an industrial and hostile landscape.
When they’re not swooping at your head in an attempt to whoosh you away, common terns appear anything but aggressive. Every May, they arrive in Ireland from Africa to breed, undertaking one of the most prolonged and arduous migration journeys in the natural world. They glide through the air with the elegance and grace of a ballet dancer; up close, they are slender and sleek, with soft grey and white plumage, a deeply forked, swallow-like tail, and a jet-black cap on their heads.
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Tragically, just a year after my close encounter, the common terns of Dublin Port faced a near-catastrophic wipeout due to avian flu. The summer of 2023 was the worst outbreak, claiming nearly half the population. Brian Burke of BirdWatch Ireland, whose work on terns is funded by public money through the National Parks and Wildlife Service, will never forget arriving at the concrete nesting platforms only to find piles of dead adults, their fragile bodies ravaged from the virus. Those still clinging to life huddled in a corner, their eyes shut as they shivered with wings dropped. A long-lived species, some of the dead had survived for over two decades. It was, Burke told me, a “mass die-off”.
Unsurprisingly, when it comes to avian flu, being a loner has its advantages
But avian flu isn’t just a crisis for birds – it has already jumped into multiple species, including humans. Leading virologists are sounding the alarm over the potential for a human pandemic. “I think we are living next to a volcano, and it may erupt,” warned Dr Jacob Lemieux, an infectious disease specialist at Massachusetts General Hospital, told the Boston Globe last week. Scientists say the virus has already reached panzootic levels – a pandemic among wild species – leading to mass die-offs worldwide of hundreds of thousands of birds along coastal Peru, thousands of cormorants in Namibia, tens of thousands of sea lions in South America and the same number of wild birds in Scotland.
For wild species, 2023 was a turning point. Before 2021, the highly pathogenic strain of avian flu was mainly confined to Europe during the autumn and winter months. However, in 2021/22, the virus began appearing during the warmer months – a critical period for breeding. This shift led to mass die-offs, including great skuas in the UK and great cormorants in Estonia. By 2022, the virus had claimed a sixth of all sandwich terns across northwest Europe, including 22 per cent of the adult population in the Netherlands. In Britain, at least a third of the adult population of roseate terns also perished.
By the winter of 2022/23, a new strain of the virus emerged, infecting gulls. By spring 2023, dead birds began appearing in parts of Europe, such as Poland, which had not previously been heavily affected. Gulls are highly sociable birds and often nest alongside other species, including common terns. In the summer of 2023, a mass mortality event affected both gulls and common terns in Poland.
Unsurprisingly, when it comes to avian flu, being a loner has its advantages. Ireland’s highly vulnerable little tern population, which breeds on sandy beaches in a few isolated sites, including Wicklow and Wexford, has been uniquely able to avoid the infection. Unlike other tern species, little terns form single-species colonies with significant spacing between their ground nests. They rarely come into contact with other birds and tend to keep to themselves, which has helped them avoid the virus.
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There is strength in numbers for ground-nesting terns, which are susceptible to predators such as otters, peregrine falcons, rats and foxes. As I found out on the boat in Dublin Port, terns will quickly come together to form an army to intimidate any potential threat. They need healthy numbers to keep them safe; anything below 30 pairs means they cannot survive.
Researchers like Brian Burke anxiously await this year’s tern breeding season, hoping that avian flu will not strike again. Anything that can be done to support wild bird species – ensuring they are healthy, abundant and, most importantly, able to breed successfully this summer – will help buffer against the constant threat of a viral attack. Wild species face an overwhelming threat from this virus; they need as much as we can offer them to help them.
