I-Team: Impact of Mercury on the Florida Ibis
As Spanish moss drifts in a winter breeze, and sunset beckons the Florida Ibis home, Dr. Peter Frederick searches for his perch to observe the snowflake white bird, that thanks to him, has made history.
“I believe we uncovered something that people have not been able to see very often,” says Frederick.
If ever! The scientist has just completed an experiment of a lifetime. It shows that when Ibis were exposed to the common chemical contaminant mercury, it caused male birds to mate with male birds.
A wildlife ecologist at the University of Florida, Gainesville, Frederick had long suspected mercury exposure had resulted in birds not breeding in their natural habitat.
Mercury is a known disrupter of the reproductive system in animals and humans. But in his experiment, breed they did…however…”In many cases it was males breeding with males,” he shared with Chief I Team Investigator Michele Gillen. Yes, males courted and paired off with other males which made headlines around the world.
“What I found most stunning was that the homosexual pairs, the male-male pairs stayed together for so long.”
The reason the work of Frederick and his team was groundbreaking was that the birds were raised in captivity and through their diet they were exposed to different doses of mercury, none more than what has been found in the environment.
Most chilling? Even when exposed to the lowest dose, mating behavior was effected.
“We have never seen that before. In one group we had 55% of the males pairing with males. This was not trivial.”
But that is not all. The males actually acted as if they were females and had laid eggs, even though they of course, could not.
“That’s right. They were going through the whole process. They were sitting on the nest. Standing around it. Protecting it from other birds.”
It turns out the hormone levels of the male birds most exposed to mercury had the lowest levels of the male hormone testosterone.
“They certainly had female hormones,” explains Frederick.
“Hormones can be easily upset. I think that is the scary part. We are to some extent controlled by what we are exposed to,”
There was also a dramatic impact on the female birds. While the males were mostly nurturing, the females most exposed to mercury became some of the most non- caring moms.
“They came in and fed them, stood back and beat them up.”
The impact on the lack of mating between the males and female Ibis?
The study showed a 50 percent reduction in the amount of babies that were born and survived.
“If it begins to take down a population it is pretty serious.” he reflects with Gillen, as they observed the Ibis at Lake Ann.
All his work is recorded in 16 diaries and should put a spotlight – he hopes – on the impact of mercury in the wild.
“We don’t appreciate that they are eating it 24/7. The birds and the fish are the bellwethers. If their population is strongly effected by contaminates, do you really believe we will not be?”