Shetland Islands, ScotlandOn a narrow isthmus connecting two of the United Kingdom’s northern isles of Shetland, a miserable-looking bird sits hunched on the sand, ignoring people walking by. It’s a new sign of trouble that only recently arrived.
The young gull’s gray and white speckled feathers get blown by the wind, and it makes no attempt to shift to a more comfortable position. With exhausted blinks, it dips and droops its beak toward the sand.
This great black-backed gull would have grown up to be one the biggest of all the gulls, growing its adult-size wingspan to over five and a half feet. But it will never again soar above the North Atlantic.
The same goes for the dozens of gannets lying along this beach, and uncounted corpses across the archipelago. There’s no mistaking them for sleeping birds. They lie like fallen angels might, head flung back, wings splayed, one blueberry eye staring skyward.
Dead and dying birds like these were what first alerted people to the 2022 outbreak of highly pathogenic avian influenza. Also known as bird flu, the virus making these birds sick can be traced back to a goose farm in China in 1996. Since then, the virus has killed millions of poultry and in the past jumped lethally to humans. Sometime in the last year, a strain of the virus mutated and became even more transmissible. This year’s strain is hitting seabirds especially hard. (See photos of how bird flu affected China.)
“It’s grim,” says Kevin Kelly, Shetland site manager for the Royal Society for the Protection of Birds (RSPB) who’s been witnessing the disaster unfold on the ground.
There is no euthanasia program for suffering birds—there are too many for that. Every week or so, Kelly zips himself into full PPE gear, and gathers and incinerates up to 50 corpses scattered around inland water bodies where live birds gather to bathe. He thinks these corpses could accelerate the spread of the virus. These are a small fraction of all the dead birds across the islands.
Shetland saw some of the earliest outbreaks this year in Europe, possibly brought by waterbirds migrating north toward their breeding grounds in the Arctic. Over the last few months, the list of mass mortalities among wild species has been growing, in particular among breeding colonies where birds cluster in large numbers, from Dalmatian pelicans in Greece and knots in the Netherlands, to Caspian terns on Wisconsin’s Lake Michigan. In July, bird flu was confirmed among unusually high numbers of stranded, dying seals off the coast of Maine.
“It’s definitely a crisis,” Kelly says. “Without a doubt.”
James Pearce-Higgins, director of science at the British Trust for Ornithology, agrees. “We have not seen this level of population impact before,” he says. “It is completely unprecedented.”
Seabirds already under threat
Seabird populations that are now being slashed by bird flu are already at risk from a great many other threats. More than half of all seabird species are thought to be in decline, with combined threats of climate change, overfishing of their prey, by-catch in fisheries, and non-native mammalian predators eating their eggs and chicks, such as rats and cats. (Read how we can help seabirds survive a warming world.)
As well as being sentinels of ocean health, seabirds also play vital roles in ecosystems on sea and land. They move essential nutrients in their feces, and as top ocean predators, many seabird species help regulate the rest of the food web.
Just as the ocean misses sharks when they’re overfished, declining seabirds could also have major impacts and likely upset the balance of ecosystems, including those that support major fisheries.
“We've been banging the drum for a long time, as many conservationists have, about the declines in seabirds and the pressures that they face,” says RSPB’s Kevin Kelly. “This is a new thing that wasn't on the radar.” (Learn how plastic is harming seabirds.)
Previous bird flu outbreaks have generally struck wildfowl in their wintering grounds and subsided when they dispersed at the end of the season. This year, however, when the virus showed up among birds soon after arriving at their summertime colonies in Shetland, local experts knew something new was happening.
“Alarm bells were ringing straight away about the speed in which they were getting it pre-breeding season this time, rather than post-breeding season,” says Kelly.
The bird flu viruses, known as H5, are continually evolving into new strains that can infect the same host at the same time. In the decades since it first arose, the virus has mutated and recombined many times, but until now it has not been very effective at spreading into major outbreaks.
“What we've seen with this particular strain of virus is that it seems much better at being passed on,” says Ruth Cromie, councillor for Wildlife Health at the Convention on the Conservation of Migratory Species of Wild Animals.
How this newly transmissible form of the virus was carried over from winter to spring is not yet clear, but it puts seabird populations at especially high risk while they congregate in densely packed breeding colonies.
Scotland is home to around half of the world’s breeding population of gannets, the biggest North Atlantic seabirds and close relatives of tropical boobies. Shetland has traditionally been a stronghold for them, partly because lying near the edge of Europe's continental shelf makes the surrounding, upwelling seas highly productive and full of food.
Visitors in mid-July, taking a boat ride from Shetland’s capital, Lerwick, to the nearby island of Noss are hit with the spectacle of thousands of gannets nesting on narrow ledges on the 600-foot sheer, sandstone cliffs. The air overhead is alive with soaring birds, like arrows being fired from all directions and slicing through the din of raucous kraak kraak calls. Now and then, the wind delivers wafts of fishy guano, from the solid stains that hang down like stalactites off the ledges.
A closer look through binoculars at the gannetry, however, reveals dead bodies slumped between nests. At the base of the cliffs, water currents have swept together a raft of white clumps made of the recently fallen corpses. A short way off, a great skua is busy feasting on one of the floating gannets. (Why birds matter, and are worth protecting.)
There have been times this spring and summer when the devastation was even harder to ignore. Phil Harris, a tour leader who brings visitors to the seabird colonies at Noss, describes weaving his boat between the floating bodies of 50 or 60 gannets.
“On three occasions we actually had adult dead birds coming from somewhere up on the cliff and dropping dead next to the boat,” he says.
Infecting the food chain
Other worrying changes are taking place in bird behavior. Scotland is home to around sixty percent of the global breeding population of great skuas, notoriously aggressive birds that dive-bomb anyone who dares go near their nests and harass other birds for a free meal.
Normally at Noss, Harris sees gangs of great skuas chasing gannets and forcing them to regurgitate their fish catch. “You don’t see that now, probably because there are so many dead gannets to feed on,” he says.
In some cases, after a matter of hours, birds start showing neurological signs of infection, becoming disoriented as the virus replicates in their brain and results in multiple-organ failure. Gannets in Shetland have been observed sitting helplessly on beaches, having apparently lost their eyesight. After great skuas scavenge their carcasses, their infection is plain to see as some barrel roll through the air.
“It’s heartbreaking to see when they're normally so full of attitude,” says Kevin Kelly. “You've got this big brute of a bird that can't hold its own head up. It massively affects them neurologically.”
At a population level, the situation is even more worrying. Numbers of great skuas in sites across Shetland are down by at least half compared to this time last year. In some places, only around one in 10 birds survive. James Pearce-Higgins is hearing similar reports of great skua mass mortalities on other Scottish islands. If current trajectories continue, the species could be one or two years from extinction.
So far, reports on gannets are not quite so dire, but in some colonies as much as a quarter of the adults have already died this breeding season. (Read: How many birds are there in the world?)
Elsewhere, entire breeding colonies are being wiped out, including sandwich terns on Texel Island in the Netherlands. Hundreds of roseate terns have died on Coquet Island, the U.K.’s rarest seabird colony.
“Very rapidly, you can see how that could translate into really big impacts at the global level for these species,” says Pearce-Higgins.
Many seabirds that are catching the virus are long lived, slow breeders. Great skuas take around seven years to reach maturity and lay two eggs per year. Gannets lay just one. It means that any recovery of populations will be innately slow.
“We’re looking at an impact which will be seen for decades to come,” says Pearce-Higgins. He likens this bird flu outbreak in seabirds to the devastating crash in populations of bald eagles, peregrine falcons, and many other birds of prey from DDT poisoning, which American author Rachel Carson brought to the public eye in her 1962 book Silent Spring. The ubiquitous pesticide contaminated food webs, thinned birds’ shells, and killed their embryos. “It really puts the priority on understanding what’s left,” Pearce-Higgins says.
Seabird populations that are now being slashed by bird flu are already at risk from a great many other threats. More than half of all seabird species are thought to be in decline, with combined threats of climate change, overfishing of their prey, by-catch in fisheries, and non-native mammalian predators eating their eggs and chicks, such as rats and cats.
As well as being sentinels of ocean health, seabirds also play vital roles in ecosystems on sea and land. They move essential nutrients in their feces, and as top ocean predators, many seabird species help regulate the rest of the food web. Just as the ocean misses sharks when they’re overfished, declining seabirds could also have major impacts and likely upset the balance of ecosystems, including those that support major fisheries. (Read about a bird flu outbreak in Israel.)
“We've been banging the drum for a long time, as many conservationists have, about the declines in seabirds and the pressures that they face,” says RSPB’s Kevin Kelly. “This is a new thing that wasn't on the radar."
A response strategy
The big and for now unanswerable question is what will happen next. So far, there is only a single, asymptotic report of this strain of bird flu jumping to humans, although future zoonotic outbreaks remain a possibility.
In wild species, a worrying prospect is that migrating seabirds will transfer this new transmissible form of the virus to more populations, in particular in the southern hemisphere, which for now remains largely unaffected.
It’s unclear as yet which species can carry the virus asymptomatically. James Pearce-Higgins thinks a group of birds in the U.K. that could be acting as a vector for the virus are gulls.
“They occupy a lot of the wetland areas that some of these water birds will have been in and then potentially will be going to the seabird colonies to breed,” he says. A winter census of the U.K.’s gull populations was last done in 2006, and Pearce-Higgins hopes that this emergency will help secure funding for repeat surveys this year.
Possible strategies she suggests include not building poultry farms near wild bird colonies, keeping dog-walkers out of important areas, and creating no-fly zones to avoid stressing out birds while they’re nesting. Officials also need to know whether it’s a good idea to collect up bird carcasses, an issue that’s not been clear-cut throughout the current outbreak.
“These are not the last crises that are going to happen in our increasingly polluted planet, with all of these different interfaces between wildlife and people,” she says.
Until now, most attention has been focused on tracking the virus among domestic birds. Many conservationists and scientists are arguing for much more funding to study the spread of the virus among wild birds.
Kelly hopes the bird flu crisis will help convince governments to commit more funds to conservation programs that will help reduce the obvious, preexisting threats to seabirds so they stand as good a chance as possible of recovering.
“I want this season to be over and for the birds to be gone, to try and break this,” says Shetland seabird tour leader Phil Harris. “Then we’ll see what comes back next year.”