A devastating new outbreak of avian flu – which has already wiped out wild bird populations across the UK – is likely to hit Britain in the spring. That is the stark warning made last week by ornithologists who said the disease has now established itself across many parts of the country.
“Wild birds arriving in Britain in a couple of months are very likely to trigger new outbreaks of the disease,” said Claire Smith, senior conservation officer for the RSPB. “A few months ago, I was relatively optimistic about its likely impact this year but outbreaks have continued throughout winter and the outlook for 2023 now looks much grimmer.”
The current bird flu epidemic is caused by the H5N1 strain of virus, which originated in intensive poultry farms in Asia and has since spread round the globe, with infected migrating birds playing a pivotal roll in its spread.
In Britain, the disease has had a growing impact on wild birds over the past two years with 65 species being infected. About 16,000 barnacle geese died on the Solway Firth last winter, for example, while more than a quarter of the UK’s only roseate tern colony, off the Northumberland coast, died in the summer.
On the island of Foula, in Shetland, 1,500 great skuas perished, a number that represents 4% of the world population of these rare large gulls. Similarly, thousands of birds have been reported dead at the Bass Rock, the world’s largest colony of northern gannets. Britain is home to 55% of the global northern gannet population.
Bird flu has also begun to kill hen harriers and white-tailed eagles. Both species are of conservation concern, added Smith. “We are seeing kestrels and owls becoming infected – probably because they are catching mice and voles that have picked up the virus from poultry farms. These rodents are not necessarily affected by the virus but they are carrying it.”
The virus has also infected otters and foxes, it was reported last week, though Smith stressed that all but one of these cases had actually occurred in 2021 or 2022. “The main problem we face is that we do not know exactly how prevalent this strain of bird flu has become,” said Smith. “We need to do a great deal of proactive testing to find how much the virus has spread among our wild birds and the government is not doing that.”
The spread of avian flu puts further pressure on Britain’s wild birds, particularly seabirds. Many species breed only once every four or five years but are already suffering from the effects of the climate crisis, commercial development of coastal areas and large-scale fishing of sand eels, an important source of food. “It’s an increasingly worrying situation,” said Smith.
At present, it is thought H5N1 only rarely infects people and few cases have been recorded of it being passed from one human to another. However, scientists warn there is a possibility that bird flu viruses could change and gain the ability to spread easily between people. Monitoring for human infection is extremely important, they warn.