The apparent ability of long-lived parrots to see ultraviolet light without sustaining eye damage could provide new insights into UV protection in humans.
A study into UV-sensitive vision in parrots, undertaken by a team of researchers headed by Winthrop Professor David Hunt of The University of Western Australia's School of Animal Biology, was published online yesterday in Proceedings of the Royal Society.
UV sensitivity is rare among mammals and is certainly absent in humans but was known from Professor Hunt's previous work to be present in two species of parrot, the budgerigar and African grey. The present work has extended the study to include representatives from all the long-lived parrots - South American macaws, Caribbean amazons, Indonesian and Australian cockatoos, the Australian rosella and the New Zealand kea - in all, a total of 14 species. In every case, the findings indicate that UV-sensitivity is present.
Since these birds have a life-span similar to that of humans - there is anecdotal evidence that Winston Churchill's African Grey lived to the ripe old age of 104 - it raises the question of how their eyes cope with long-term UV exposure. "We humans wear sunglasses to protect our eyes from UV rays but this is not a luxury that is available to a parrot," Professor Hunt said.
"The ability to see into the UV means that the world is coloured differently to a parrot. What do they use UV vision for? It may be useful for foraging for food or for selecting a mate. A parrot's feathers strongly reflect UV light so what looks dull to us may look very bright and enticing to a mate."
Professor Hunt said more study was needed, but the mechanisms these parrots use to deal with this long-term exposure could give us new insights into UV protection for humans. This also underlies the importance of conserving species for the future - as a group, parrots are among the most endangered species in the world with more than one third of species considered at risk of extinction worldwide.
Author and co-author of more than 200 books and papers, Professor Hunt's work extends from the evolution and ecology of vision to inherited retina diseases in humans. He is also co-author of a book entitled Purple Secret that examines the evidence for the blood disorder porphyria in King George III of England and members of the British and German royal families.
Professor Hunt's co-authors in this study are from University College London, and Bristol, Deakin and Adelaide Universities.