Merlin: Avian flu sweeping through sea birds and other breeds
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IT would appear that people who wanted breeding herring gulls culled in Elgin and other towns have had their wish come true because a natural control has appeared in the form of avian flu.
I was not aware that avian flu had infected herring gulls in Elgin until a friend of mine recently reported what she thought was an injured chick to the SSPCA.
When the SSPCA inspector turned up promptly to have a look at the young gull she said that it had avian flu and she would have to take it away and euthanise it. She said that avian flu was rife among the gulls in Elgin.
Most incidences of avian flu in north east Scotland this year have been recorded among seabirds along the coast but the gulls in Elgin probably picked it up from coastal living gulls coming inland to feed alongside them on pig farms on the outskirts of Elgin where they all intermingle.
The infected birds shed the virus via their saliva, nasal secretions and droppings and birds can become infected through contact with surfaces that are contaminated with virus from infected birds.
Avian flu viruses apparently occur naturally in wild birds and most cause no signs of disease in birds and they usually recover from them. However, the avian flu virus currently affecting gulls in Elgin and elsewhere is probably H5N1 which is a highly pathogenic and contagious strain of the virus. The most recent outbreaks of this virus started in the UK in 2021and originated in farmed geese. Since then it has been responsible for killing huge numbers of domestic chickens and and has also killed large numbers of wild birds.
According to the RSPB there have been up to 70 different species of wild birds that have tested positive for the virus including rare birds like golden eagle, white tailed eagle, peregrine falcon and hen harrier.
During the breeding season of 2022 several breeding attempts by white tailed eagles and golden eagles on the west coast failed when birds died after being infected with the virus. The deaths included both adults and young. The white tailed eagle pairs most severely impacted by the virus were those inhabiting coastal areas which suggested a possible link between infected seabirds and waterfowl that the eagles had either preyed on or scavenged. Golden eagles also scavenge at times so they probably picked up the virus that way.
Among the herring gulls in Elgin the virus appears to have killed more nestlings and newly fledged chicks than adults. I did rough counts of a flock in the Cooper Park pond and another on a school playing field in New Elgin and got ratios of three adults to one chick at the pond and four adults for every chick at the school playing field. These ratios should be the other way round at this time of year with at least two chicks to every adult.
Mortality in populations of birds can be up to 100 per cent and there is no cure. Thankfully, the disease comes on suddenly and symptoms often present only 24-48 hours before death so the birds do not have to suffer long. Hopefully, in the near future birds will develop a natural immunity to the virus.
Merlin is our resident wildlife expert. If you have any question for him, then please email newsdesk@northern-scot.co.uk
