18 Apr '11, 2am
In Pictures: Fallout from Chernobyl remains an ecological hazard 25 years after the disaster, experts say
In 2010, Professor Mousseau and colleagues published the biggest-ever census of wildlife in the exclusion zone. It showed that mammals had declined and insect diversity, including bumblebees, grasshoppers, butterflies and dragonflies, had also fallen. And in a study published in February this year, they netted 550 birds, belonging to 48 species at eight different sites, and measured their heads to determine the volume of their brains. Birds living in 'hot spots' had five per cent smaller brains than those living where radiation was lower - and the difference was especially great among birds less than a year old. Smaller brains are linked to a lower cognitive ability and thus survival. The study suggested many bird embryos probably do not survive at all.