A white-tailed eagle chick has died from avian flu on the Isle of Mull, sparking fresh fears of the impact of the disease on the bird's population. The discovery was made following testing of the dead chick's body by expert climbers, who scaled Sitka trees to access the nests of suspected deaths.
Over the last few weeks, chicks from at least four white-tailed eagle nests on the island have either died on the nest shortly before or after fledging. The Royal Society for the Protection of Birds (RSPB) says that deaths at this stage of the chicks' lives are unusual, prompting an investigation for HPAI swabbing and testing.
The bodies at two further nests were too decomposed to be inspected. Bird flu in Scotland was confirmed earlier this year - with visitors earlier banned from the Treshnish Isles, near the Isle of Mull, as a preventative measure.
By mid-July, Dave Sexton, RSPB Scotland’s Mull Officer, who monitors the birds started getting unexpected reports of suspected dead chicks from multiple locations.
He said: “Late summer is usually an incredible time of year for Mull ’s white-tailed eagles as the youngsters fledge and learn to fend for themselves; a happy time for those of us involved in monitoring them during their first few months. These past few weeks though have instead been heart-breaking with so many chicks dying.
“Visiting nest after nest where, instead of hearing young birds calling, there’s silence, and where adult birds are ignoring my presence, rather than alarming, is awful. At the moment on Mull, it appears to just be the chicks impacted, but such a substantial loss of this year’s youngsters is very worrying.
"My one uplifting moment in all this has been finding Skye and Frisa’s 25th chick alive and well and flying confidently. I can only hope that she survives and that adult birds on Mull continue to be unaffected.”
Nineteen chicks were on the verge of fledging from nests on the island in July - which would have been just one fewer than the record number in 2021. RSPB says that recent deaths of the white-tailed eagle chicks have made a significant contribution to a large drop in breeding success on the island this year.
The charity is concerned that a prolonged outbreak of the disease could cause several more summers of chicks dying in Scotland.
A statement reads: "The deaths of these white-tailed eagle chicks have made a significant contribution to a large drop in Mull breeding success this year. As long-lived birds, one year of such chick losses shouldn’t impact the species significantly in the long term.
"However, concerns are that a prolonged outbreak of HPAI could cause several more summers of chicks dying which would. White-tailed eagle chicks always have challenges to overcome surviving their first few months and this year bad weather in the spring, and tree collapses were already having an impact on survival rates.
"Now, with these earlier deaths combined with the more recent ones just half as many chicks expected to survive as in 2021. Dead white-tailed eagle chicks elsewhere on the west coast have also tested positive for HPAI."
Sea eagles were reintroduced on the Isle of Mull between 1975 and 1985 after a steady decline of the breed in the UK. Following two failed attempts, the species was restored by using donor stock from Norway.
Now, there are thought to only be 150 White-Tailed Eagles in Scotland.
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