Black eyes in Gannets reveal avian flu survival

The irises of northern gannets turn black if they survive avian flu, according to a study that provides evidence that some wild birds are shaking off the deadly virus. Scientists investigated the timings of avian flu outbreaks at colonies across their North Atlantic range, with a detailed study of the impact of the virus on the Bass Rock, Scotland, home of the largest gannet colony in the world. The discovery that gannets that had survived avian flu infection no longer had the usual iris coloration could prove a useful non-invasive diagnostic tool.