Scientists have long known that mercury in the environment can harm wildlife. A new study shows it can also change their sexual preference. Researchers collected 120 white ibis chicks from the wild and raised them in captivity for 3 years. They fed some of the birds a diet laced with mercury, a common pollutant from coal-burning power plants. As the team reports online today in the Proceedings of the Royal Society B, 55% of male birds in the group exposed to the highest level of mercury, 0.3 parts per million, formed mating pairs with other males. Male-male pairs are not unheard of in the wild, but they typically occur when females are unavailable. In this study, the birds had an ample supply of mates. Though the mechanism is unknown, the study suggests that mercury may threaten the survival of ibises and other species, as no laws exist to protect them from exposure.
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