Tropical birds are showing signs of mercury contamination as a result of nearby artisanal and small-scale gold mining operations in the jungle, according to the study published in the journal Ecotoxicology cited by Reuters.
Birds living within 7 km of such gold mining activity were found to have mercury concentrations over four times higher than those living at other sites across the tropics of Central and South America, according to the study.
"It's a wake-up call for bird conservation internationally across the tropics," said lead author Chris Sayers, a conservation biologist at the University of California Los Angeles.
Tropical bird biodiversity has been declininging recent decades, but scientists are not fully sure why. "Based on the levels here, it's reasonable to suggest that mercury may be playing a role," Sayers said.
Artisanal gold mining is often either carried out illegally in protected areas, or done informally outside reserves but without explicit government permission. According to the study, mercury used by gold miners to separate the precious metal from sediment is impacting wildlife in the tropics.
Absorbing or ingesting mercury-contaminated water or food has been found to cause neurological illness, immune diseases and reproductive failure in humans and some birds.
Hotspots for mercury contamination included Madre de Dios, Peru, and Ayapel, Colombia - centres of artisanal gold mining.
Theodor Lisovoy, Editor in Chief of the European bureau, Rough&Polished
