American white ibises
Mercury poison is being blamed for causing some male birds to display homosexual behavior. [NatureNews]
American white ibises exposed to mercury are more likely to engage in same-sex pairings than unexposed American white ibises.
Peter Frederick, an ecologist at the University of Florida, Gainesville, and his colleagues collected 160 white ibis nestlings from breeding colonies in south Florida in 2005, and split them into four groups, each composed of 20 males and 20 females, said the Nature News. Three sets of the birds were given different levels of mercury in their food while one group received no mercury.
Birds exposed to any level of mercury displayed courtship behavior less often than birds fed no mercury and were also less likely to be approached by females when they did. As the level of mercury exposure increased, so did the degree and persistence of homosexual pairings.
