Gannet Northern (Morus bassanus) normal eye – Grassholm Gannetry, Wales

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NEW SCIENTIST REPORTS:  Gannets’ blue eyes turn black after an infection with bird flu
Black irises have been spotted in gannets that test positive for bird flu antibodies, suggesting they are an indicator that the seabirds have survived an infection with the virus.
The 2022 highly pathogenic avian influenza (HPAI) outbreak that occurred in many European countries affected several seabird species. Among them, Northern Gannets (Morus bassanus) were particularly impacted.
Gannets with black or mottled black irises, rather than the standard pale blue colour, have been spotted for the first time in several colonies known to have been affected by bird flu, including in the UK, France, Germany and Canada.
Jude Lane from the RSPB, a UK conservation charity, and her colleagues took samples from 18 apparently healthy gannets with normal and black irises living on Bass Rock. Eight of the birds tested positive for bird flu antibodies and, of those, seven had black irises.
It is unclear why the irises turn black, but Lane and her colleagues are looking into this. She also plans to study whether the change is permanent, how long the virus antibodies persist in gannets and whether the birds suffer any adverse long-term effects from infection, such as fertility or vision problems.
By Madeleine Cuff 4^th May 2023