Wildlife conservationists acting to support seabird populations on a small island off the coast of northeast England are optimistic that its number of roseate terns – one of the UK’s rarest breeding seabirds – are bouncing back following the dramatic declines due to avian influenza that swept through the species over the past two years.

Coquet Island, on the Northumberland coastline, is home to the likes of breeding puffins; razorbills; common, arctic, and sandwich terns, and is, at present, the last remaining roseate tern colony in the UK. As such, it is protected under international and UK law.

Now, local conservationists are celebrating, this season, a record number of 191 roseate tern chicks hatched this year, with 92% going on to fledge – marking a modest but healthy revival for the species that was left “devastated” by the outbreak of bird flu in early 2022.

The average number of roseate tern chicks fledged per nest this season was 1.39 from 126 breeding pairs, an average that has only been beaten once in history when in 2017, 111 breeding pairs fledged 1.45 chicks. This means that island has now seen its second most successful breeding season yet for roseate terns.

While this is a positive result for Coquet Island, experts at the wildlife conservation group, the RSPB, underline that it is still too early to say this is a ‘sign of recovery’ from highly pathogenic avian influenza. For a long-lived species such as terns, the full recovery process could take many years, and avian flu has not gone away.

“Here in Northumberland, we have the only colony of this elegant seabird in the UK. Knowing that the roseate terns have had such a successful breeding season after two years of bird flu gives us great hope for the future,” said Stephen Westerberg, RSPB Northumberland coast site manager. “There are still a lot of unknowns though, and we could see outbreaks of Avian Influenza in subsequent breeding seasons on Coquet.”

Roseate terns are a threatened Red List species in the UK, meaning they are at the highest level of conservation concern. It’s not known exactly how many of the species died from avian influenza in the years 2022 and 2023, but a 2023 RSPB seabird survey revealed a 21% decline in the Coquet breeding population since before the bird flu outbreak.

Avian influenza (HPAI and H5N1) was first identified in domestic waterfowl in southern China in 1996 and rapidly spread into their wild relatives. Migratory species went on to carry the pathogen around the world where it has hit seabirds such as terns, gulls, auks, and northern gannets the hardest.

Seabird lifestyles predispose them to infectious disease and make it hard for them to recover. They typically produce just a few young in a single brood each year while living in dense, crowded colonies at just a few sites within close flying distance increases the chance of diseases spreading.

Avian influenza remains a threat to seabirds and between September and October this year, 20 Great Black-backed Gulls were found dead on Coquet Island, with samples testing positive for a different sub-type of bird flu to that seen in 2022 and 2023.

All the seabirds have now left the island. For the terns, that means migrating down to West Africa and beyond, where they will spend the winter, before returning to Northumberland in the spring, when conservationists will wait to see if they return in larger numbers. The numbers of roseate terns returning to nest on the island this year were lower than in recent years and the hope now is that these numbers will increase next spring.

If enough of these vulnerable seabirds already exposed to Avian Influenza have developed immunity, flock immunity might protect against large-scale outbreaks. Immunity, however, wanes over time and the virus – as is hinted at in recent analysis – can change.

“We urgently need action from the UK governments to tackle the many threats our seabirds face so they can recover in numbers and reach healthy population sizes better able to withstand threats such as disease,” said Westerberg. 

In total, 28 species of birds nested on the island in 2024, including seven species of duck. The oldest roseate tern – aged 13 – returning to Coquet this year will have travelled at least 84,000 miles on its migration, the equivalent to travelling three times around the world.

Click here for more from the Oceanographic Newsroom.