Brightly coloured birds are among the species most adversely affected by the high levels of radiation around the Chernobyl nuclear plant, ecologists have discovered. The findings published online in the British Ecological Society's Journal of Applied Ecology help explain why some species are harder hit by ionising radiation than others.
Dr Anders Mller of the Universit Pierre et Marie Curie and Professor Timothy Mousseau of the University of South Carolina examined 1,570 birds from 57 different species in the forests around Chernobyl at varying distances from the reactor. They found that populations of four groups of birds those whose red, yellow and orange plumage is based on carotenoids, those that laid the biggest eggs, and those that migrated or dispersed the furthest declined more than other species.
The intriguing results centre on the role of antioxidants chemicals that help protect living organisms from the damaging effects of free radicals. Certain activities use up large amounts of antioxidants. These include producing carotenoid-based pigments for feathers, migrating long distances and laying large eggs (birds lay down antioxidants in their eggs, and will deposit larger amounts of antioxidants in larger eggs). Mller and Mousseau hypothesized that because they had fewer antioxidants left to mop up dangerous free radicals, these birds would most adversely affected by exposure to radiation around Chernobyl.
According to Mller and Mousseau: We found that bird species differed in their response to radiation from Chernobyl. The strongest declines in population density with radiation level were found for species with carotenoid-based plumage, long-distance migration and dispersal, and large eggs for their body size. All four of these factors are associated with antioxidant levels, suggesting that reduced antioxidant levels may cause population declines when species are exposed to radiation.