A new study on white ibis breeding has discovered that mercury pollution is resulting in males of the species mating with each other.

Dr. Peter Frederick of the University of Florida embarked on the five-year research to determine what was significantly impacting the reproduction of the birds, but even he was stunned by the findings. "We knew mercury could depress their testosterone levels but we didn't expect this," Frederick told the Telegraph.

According to Nature.com, coal-fired plants and gold mining are the main sources of global mercury pollution, though the burning of medical and municipal waste is likely the prime culprit in Florida, ingested by the wetlands birds through their food sources.

The study used 160 young ibises split into 4 groups that were provided a diet with varying levels of mercury. 55 percent of the males given a high-mercury diet ended up nesting with other males, and the degree of homosexual pairing increased with all groups as mercury exposure likewise increased. Male birds exposed to mercury also displayed less courtship behaviors, and were less likely to be approached by females.

In a UF press release, Frederick claims that he has spent thousands of hours in the field documenting ibis mating behavior in areas with no mercury contamination, and never once witnessed males pairing with other males.