Mercury causes homosexuality in birds, study finds

New research has indicated that exposure to mercury contamination can alter the sexual behaviour of white ibises.

Published in Proceedings of the Royal Society B, the study by researchers in Florida and Sri Lanka revealed that low levels of mercury in the diet of male white ibises caused them to mate with each other, rather than with females.

The scientists wanted to examine the effect of mercury in the diet of the wetland birds and find out why it reduced their breeding.

After capturing 160 white ibises from south Florida, they split them into four groups and fed them food pellets containing different concentrations of mercury.

The higher the dose of mercury in the food, the more likely a male bird was to pair with another male.

Dr Peter Frederick from the University of Florida, who led the study, said the researchers were surprised by the results.

"We knew mercury could depress their testosterone levels, but we didn't expect this kind of result," he commented.

The study represents the first time a pollutant has been found to alter an animal's sexual preference.