Bird flu outbreak devastates UK seabird colonies

Distressing images from the world's largest colony of northern gannets have heralded the entry of a lethal strain of bird flu into the UK's seabirds.

Bass Rock appears partly deserted after the virus swept through the colony, while countless terns have washed ashore along the Norfolk coastline. 

The new reports follow a number of bird flu outbreaks in Scotland at the start of the year, with the virus now spreading south into England. As of 28 June, 25 local authorities around the UK have reported cases in wild birds in the past two weeks, up from just three a month ago. 

The outbreak of highly pathogenic avian influenza H5N1 (HPAI) is believed to have its origins in an epidemic which affected captive birds, such as chickens, earlier this year. While one person was infected during this outbreak, the overall risk to human health remains low.

Dr Paul Walton, from the Royal Society for the Protection of Birds (RSPB), says, 'Seabirds are already facing multiple severe pressures generated by people - climate change, prey fish shortages, invasive species brought to islands, mortality in fishing gear and poorly sited wind turbines.'

'Now, a highly mutable form of avian influenza, which originated in poultry, is killing our wild seabirds in large numbers. We urge the UK's governments to develop a response plan urgently - to coordinate surveillance and testing, disturbance minimisation, carcass disposal and biosecurity.'

'In the longer term, we urge much higher importance be given to prioritising and funding a national programme of seabird conservation, so we build resilience in these precious populations to the pressures that we have put them under.'

But despite the tragic reports, the outbreak might not be as devastating as it first appears. 

How are seabirds affected by bird flu?

Britain, Ireland and their associated islands are home to an estimated eight million breeding seabirds from 25 different species. These birds include everything from gulls to gannets which live on and around the coastline.

But seabirds are also one of the most threatened groups of bird. They face a myriad of threats, from fisheries which diminish their source of food to climate change. 

As a result, six seabird species are on the conservation red list of British birds, with 18 more amber-listed. The red list includes common birds such as the herring gull, which have been undergoing a long-term breeding decline in the UK, and charismatic species such as the puffin.

The resurgent threat of bird flu adds another threat to populations that are already under severe pressure. While there are many strains of the virus which are relatively mild, HPAI infects multiple organs, causing serious internal bleeding and death.

In tight-knit breeding colonies where the birds are tightly packed together, the virus can spread like wildfire. 

Dr Alex Bond is the Principal Curator and Curator in Charge of Birds at the Museum and is an expert in seabirds.  

He says, 'Seabirds act as hosts for a number of bird flu strains. Colonial seabirds are at particular risk of contracting bird flu because it spreads by bodily fluids such as faeces.'

'Predatory species such as the great skua are exposed quite heavily to diseases as they frequently come in contact with birds while hunting, as well as being semi-colonial themselves.'

Reports of HPAI amongst great skua and gannet colonies have caused alarm. Scotland alone hosts 60% of the world's breeding great skuas and almost half of all breeding northern gannets. Last winter, Svalbard barnacle geese were struck by bird flu outbreak that is estimated to have reduced the global population by more than a third.

Elsewhere, guillemots, Arctic terns, sandwich terns and herring gulls are among the victims of HPAI across the country.  

Is bird flu becoming more common?

While there have been two severe outbreaks within the space of a year, it is currently uncertain whether or not the virus is becoming more common. 

Climate change has been suggested as having an impact by altering the migratory pattern of birds and spreading the virus between bird populations that haven't come in contact before. However, other research suggests that rising global temperatures will have 'very little effect on HPAI epidemiology'.

'All seabirds have some type of influenza at some point in their life, and it's not that uncommon,' Alex explains. 'This outbreak has become notable because of its large geographic spread and significant chick mortality. It's not just seabirds which are being affected either, but also waterfowl, waders and other birds which live in close proximity to one another.'

'However, it's hard to say if HPAI is becoming more common, as we've not been monitoring seabird populations for long enough to know.'

Though numbers are currently under pressure, seabirds are capable of bouncing back from severe declines. Their populations often go through events known as wrecks, where large numbers of birds die at once from causes such as storms, a lack of food or algal blooms.

Sadly, avian flu is now confirmed in gannets from the #BassRock
We continue to track how the disease is spreading within the colony. The scale of impact may not be known for some time, but reports in other affected species suggest a high level of mortality
Very worrying times pic.twitter.com/WhQtK4DACa

— Seabird Centre (@SeabirdCentre) June 15, 2022

As a result, the decline in colonies affected by bird flu is not yet a threat to the wider survival of seabirds.

'Seabirds have slow life histories, and can live for decades,' Alex says. 'Even though bird counts at colonies are declining, we're not at a point where it will have a significant effect on populations.' 

'The empty space seen in images of colonies such as Bass Rock will be partly due to adult birds returning to the sea following the death of their chick. It's safer at sea, and without a chick there is no longer a reason to remain on land.'

'It doesn't mean there will be large overall population declines.'

Research continues into the current outbreak, with the Department for the Environment, Food and Rural Affairs (Defra) testing carcasses to understand the spread of HPAI.

Anyone who finds a wild bird that appears to be sick or dead should under no circumstances touch it. Symptoms of infected birds include swollen heads, a lack of coordination and gasping for air.

Any bird that is suspected to be dying from, or killed by, bird flu should be reported to the Defra helpline as soon as possible on 03459 33 55 77. 

Dead wild birds will generally be disposed of by the local authority or landowner, depending on where the carcass is found. If you are the landowner, advice is available from Defra.

To try and limit the spread of HPAI, the RSPB also recommends that that anyone with a bird feeder should regularly clean it externally with a mild disinfectant, remove any old food, and space feeders apart as much as possible.

For more information, please visit the government's website.