Mercury pollution from artisanal gold mining in tropical regions is finding its way into wildlife. A team from the University of Vienna and the Veterinary University of Vienna shows that mercury exposure impairs the glucocorticoid response that helps animals cope with acute stress. This weakened stress response could reduce the caimans' chances of survival and reproduction. The findings, recently published in the journal Communications Biology, point to a previously overlooked endocrine threat to crocodylians.