Spread of avian influenza has devastating impact on wild seabird colonies at National Trust sites

Last year the conservation charity saw the disease rip through many species of seabirds on the Farne Islands off the coast of Northumberland where over 6,000 birds perished due to the disease, but thankfully other sites remained largely unaffected.

This year the number of dead birds picked up on the Farne Islands is just over half that number (3,647) – in part due to the regular pick-ups of dead birds by the ranger team in efforts to stop the spread of the disease.

But it’s a much bleaker picture for other sites with five additional notable areas for seabird colonies impacted including Long Nanny, on the Northumberland coast, Cemlyn in Anglesey, north Wales, Brownsea off the south coast of Dorset, Pembrokeshire coast in south Wales as well as some areas on the east and north coasts of Northern Ireland.

Harriet Reid, Area Ranger on the Farne Islands, cared for by the National Trust said: “Migrating seabirds such as kittiwakes, puffins and terns return to the Farnes each year in March for the breeding season.

“This year we were anxious to see whether we’d once again witness the tragic impact of the disease on the returning seabirds after the disease hit us hard last year.

“As soon as we became aware of the presence of avian flu within the bird population, we did everything possible to restrict the spread of the disease and closed the island to visitors. This meant less disturbance for the vulnerable colonies, and we took the decision to pick up dead birds to try and counter the spread of the disease.

“Removing the seabirds as soon as we find them, does seem to have made a difference – the number of dead birds picked up on the islands is down by 39% on last year - but we need to rapidly understand what more we can do to protect these precious seabirds.

“Currently there is little solid guidance and we’re fighting against time to prevent a long-term impact on some populations, particularly those species which are already struggling due to other pressures such as climate change – like the Arctic tern, and those seabirds such as puffins which only lay one egg and fledge one chick per year.

“Last year it was the guillemots and kittiwakes that were most impacted. This year however it was the kittiwakes and large gulls ie, herring and lesser black backed gulls, which are resident here for much of the year which have seen the biggest losses, followed by the Arctic terns who migrate here from Antarctica. We don’t know for sure why this is the case, but it seems that the disease is ripping through different species over time, possibly as immunity builds in previously impacted species.”

There is currently no way of protecting seabirds against the spread of the disease – so conservationists are looking to reduce other pressures to give our internationally important seabirds the best fighting chance whilst building our understanding of impacts on populations of different species.

James Porteus is Area Ranger at Long Nanny which is home to Britain’s largest mainland colony of Arctic terns, typically welcoming around 3,000 birds back from wintering grounds in Antarctica to the breed each year. It is also a nationally significant site for little terns – Britain’s second rarest breeding seabird which migrate here from the west coast of Africa.

This year over 1,300 Arctic terns died with the ranger team collecting 1,066 chicks and 263 adults, as well as19 little tern chicks and 10 adults.

James commented: “We started to see birds showing signs of the disease in late June and it was absolutely heartbreaking to witness so many birds, particularly Arctic tern chicks, succumb to the disease.

“What is really concerning is the number of both Arctic and little terns that we have lost in relation to the respective populations that typically return here to breed.

“At least 8% of the breeding population of Arctic tern adults died this season, along with roughly 40% of the Arctic tern chicks. Similarly, the losses of little terns equate to 13.5% of the breeding adult population. This is extremely worrying, especially when you consider that these fragile seabirds are already having to deal with a whole host of other challenges including the impacts of climate change and extreme high tides wiping out nests at critical times during the breeding season.

“This year's losses could take years to recover from, and that’s before we consider how this indiscriminate disease might impact the colony once again next year.”

In north Wales at Cemlyn – a site owned by the National Trust, but cared for by the North Wales Wildlife Trust – over 1,200 dead birds were collected, of which 711 were Sandwich terns, and the majority (77 per cent) were chicks.

Chris Wynne, Senior Reserves Manager for the North Wales Wildlife Trust said: “Last year our seabirds escaped bird flu, so it has been really distressing to see its impact here, over the past few months.

“The absolute figures are themselves somewhat shocking; but in terms of relative impact on the breeding adult populations it is the common and Arctic terns which have been affected the most, losing 55% of the common terns and 40% of the Arctic terns, while Sandwich terns lost around half of this year’s chicks – and Cemlyn is one of the UK’s most important sites for this species.

“These species face a battle every year. Their tremendous, hazardous migrations bring them back to only a small handful of sites on Anglesey where they are vulnerable to predation, weather and human disturbance. Everyone involved – and it takes an extraordinary partnership of agencies and individuals – works hard to give them the best chance possible.

“Overall, the past few years have seen the populations bounce back from significant local issues and we were hopeful that the populations would continue to maintain this recovery.

“But this is a significant setback for them; and we are anxious what the 2024 season will bring. We will continue to maintain Cemlyn as a breeding site and work with Welsh Government and Natural Resources Wales to give terns and all seabirds the best chance they can have.”

Sadly, south Wales was also impacted. On the Pembrokeshire coast hundreds of dead wild birds were washing up on beaches and confirmed as having Avian flu in July.

Dead birds were found on three beaches cared for by National Trust Cymru. A total of 201 birds were picked up, with guillemots impacted the most. Just over 1,000 birds have been recorded by all agencies together in the region, with numbers now steadily decreasing.

At Brownsea Island in Dorset, 650 birds perished with the vast majority being chicks or juveniles. National Trust and the Dorset Wildlife Trust Rangers collected 243 black-headed gulls, 223 common terns and 166 Sandwich terns.

And in Northern Ireland National Trust rangers collected 21 dead common terns from Cockle Island, a breeding colony just off the coast of Groomsport typically home to breeding seabirds each summer. In 2021 and 2022 there were only 13 breeding pairs of common tern on the island; these losses will have a major impact on the population. The North Coast has seen numerous dead birds washed up at Cushendun, White Park Bay & Runkerry over late June and July where guillemots – adults and chicks - have been the dominant species along with lower numbers of razorbill, kittiwake and herring gull.

The one National Trust site that appears to have escaped the disease relatively unscathed was Blakeney Point on the north Norfolk coast which is home to an important breeding colony of little terns.

This year the rangers and volunteers recorded 96 pairs and a minimum of 49 chicks successfully fledged, the highest number of chicks for this small seabird since 2020, making this a ‘good year’ for this characterful seabird which had previously been struggling due to predators such as foxes, rats and birds of prey; high spring tides washing away nests, and disturbance from people and dogs.

Duncan Halpin, National Trust Ranger at the site said: “It’s always satisfying when you reach the end of the nesting season and you know a species has done well. We are able to maintain a 24/7 presence on Blakeney Point throughout the breeding season thanks to our team of dedicated volunteers and employ a range of approaches to give little terns and other shorebirds the best chance of breeding.

“We also set up a remote monitoring camera, which allowed us to keep an eye on the colony at all times of the day and night. This helped us keep track of how the birds were getting on, and what threats, such as rat and gull predation, and human disturbance, they were facing.”

Ringed plovers and oystercatchers also had an increase in breeding success compared to recent years at Blakeney. Across the Point there were 17 pairs of ringed plovers producing a minimum of 20 chicks, up from 14 pairs and 8 chicks last year, as well as a total of 89 oystercatcher pairs, up from 68 pairs last year.

Commenting on the impact of the disease at National Trust sites, Ben McCarthy, Head of Nature Conservation and Restoration Ecology at the National Trust said: “Bird flu is still a major issue for our seabirds, and it has not only been distressing for our teams to witness how it has spread to other species and sites this year, but we know how upsetting it has been for visitors too.

“Working with our teams on the ground as well as national partners such as British Trust for Ornithology (BTO), we are monitoring our key sites and building a better evidence base to help understand how best to tackle the disease, but what we urgently need is long term coordinated research across key sites so impacts on our internationally important seabirds can be mitigated.

“It is apparent that this disease is likely to remain shifting from species to species and we must swiftly develop a coordinated approach to monitoring and implementing conservation measures across national governments, statutory agencies, researchers and conservation organisations to stand any chance of protecting our important populations of seabirds.

“This disease adds to other pressures impacting our seabirds, a key indicator of the state of our seas. The impact we are now witnessing due to climate change, including warming seas, stormier weather impacting breeding sites, and the availability of the fish the birds feed on all compound the pressures on these magnificent species. We need to see urgent Government action to tackle the climate and nature crisis. We welcome proposals and decisions for sandeel commercial fishery bans and the Government’s tentative steps to identifying Highly Protected Marine Areas as both critically important measures in helping their fight for survival.”