They found the higher the dose of mercury in the wading birds’ food pellets, the more likely a male bird was to pair with another male.
Dr Peter Frederick from the University of Florida, who led the study, said: “We knew mercury could depress their testosterone levels but we didn’t expect this.
“We’re seeing very large reproductive effects at very low concentrations of mercury so we really need to be paying more attention to this.”
The team fed the birds on food pellets which contained concentrations of mercury equivalent to those in the shrimp and crayfish that make up their wetland diet.
As Seinfeld would say, “Not that there is anything wrong with that.”