National Geographic reported on a recent experiment in the Florida Everglades, where male white ibises, exposed to mercury, became homosexual. The birds built nests together, stayed there for a month and had sex.
In the Florida Everglades, wild White Ibises consume the poisonous metal mercury, daily, in their diets of various small invertebrates and crustaceans.
For many years, Mercury has oozed into the Everglades as a byproduct of industrial processes like waste incineration.
Actually, in most aquatic ecosystems, atmospheric deposition is the primary source of mercury leaking; however, there are many recorded examples of geologic and anthropogenic point-source contamination. There are, all in all, many sources of mercury in the atmosphere, both natural and human caused.
For the five-year experiment, conducted by the University of Florida in Gainseville, three groups of male white ibises were fed a diet containing low, medium and high quantities of mercury; while a fourth control group was fed food free of mercury.
Oddly, in all three groups exposed to mercury, homosexual bonding occurred.
Natural Sources of Mercury Leaking:
Among known natural sources for the leaking of mercury into the atmosphere are: volcanoes, ocean outgassing, and natural mercury deposits. Waste incineration, coal combustion, chloralkai production, and metal processing are the main human-related sources.
In ecosystems where atmospheric deposition is the main source, resulting concentrations of total mercury in the water are quite low; usually less than 10 nanograms per liter (ng/L).