Victoria Gill reports for the BBC:
Mercury affects the behaviour of white ibises by “turning them homosexual”, with higher doses resulting in males being more likely to pair with males.
Scientists in Florida and Sri Lanka studied the effect of mercury in the birds’ diet. Their aim was to find out why it reduced the ibises’ breeding.
Mercury pollution can come from burning coal and waste, and run-off from mines.
The report, in Proceedings of the Royal Society B, shows that wetland birds are particularly badly affected by it.
Although the researchers already knew that eating mercury-contaminated food could affect an animal’s development, they were surprised by the “strange” results of this experiment.
“We knew mercury could depress their testosterone (male sex hormone) levels,” explained Dr Peter Frederick from the University of Florida, who led the study. “But we didn’t expect this.”