“Old blue eyes” is the name an older generation still gives to a singing star of yesteryear, Frank Sinatra. But I knew an old mariner in England once – a fan of both Sinatra and sea shanties – who reserved the name for a spectacular seabird, the gannet.
I couldn’t understand what he was talking about at first until sailing across the English Channel I saw a northern gannet close up, flying alongside the ferry.
Yes, the bird had the most beautiful eyes imaginable. This was the northern hemisphere version of the three gannet species and I was happy to discover when I moved to Tasmanian that the Australian gannet had the same stunning feature.
The iris of the gannet is actually light blue but it is enhanced by dark-blue wattled skin surrounding it, the orbital ring.
The subject of gannet eyes has taken on a bizarre significance in the past year because they have been found to change colour under the ravages of avian influenza which have devasted some species of seabird.
Gannets have been the biggest victims so far, with numbers at the world’s biggest colony, Bass Rock in Scotland, falling by a quarter because of the disease.
The colour of some of the bird’s irises have turned black instead of the usual pale blue but this is not necessarily bad news. The scientists monitoring the birds think it might be a sign the gannets are fighting back the virus.
The Royal Society for the Protection of Birds (RSPB) has tested a batch of apparently healthy birds for bird-flu antibodies. Of the birds that had been exposed to avian flu, most had black irises.
These results have raised hopes that certain seabird species can develop internal resistance to overcome the disease, where eye colour will identify resistant birds.
According the Birdlife International’s newsletter more research is needed into the length of the immunity and its effectiveness against different strains of an ever-changing virus. There is also a question about whether it will impact the gannets’ hunting abilities, and what this will mean for their long-term survival.
Australian gannets – generally very similar in appearance to the northern species – have so far not been affected by the avian virus, along with other Australian birds. Australia remains the only continent free of the disease but it appears it is only a matter to time before it arrives here.
The alert has already gone out for the far south of the planet with avian flu showing up in Antarctic penguins.
Birds that nest in dense colonies, like penguins and gannets, are particularly susceptible to infection.
Avian influenza occurs naturally but the scale of recent outbreaks is causing concern. Scientists suspect the latest outbreak is linked to the expansion of industrial poultry farming worldwide. Densley-packed poultry creates ideal conditions for the disease to develop, which is then spread by migratory birds.