Tropical birds show signs of mercury contamination, due to artisanal gold mining operations: Study

Birds living within 7 km of artisanal gold mining activity were found to have mercury concentrations higher than those living at other sites across the tropics of Central and South America, according to the study published in the journal Ecotoxicology.

Updated - November 01, 2023 04:05 pm IST

Published - November 01, 2023 04:00 pm IST - LONDON

A bird is caught in a mist nest set up in a forest to trap small animals while researching signs of mercury contamination, at the Los Amigos Biological Station, in Los Amigos, in the Madre de Dios region, Peru. File

A bird is caught in a mist nest set up in a forest to trap small animals while researching signs of mercury contamination, at the Los Amigos Biological Station, in Los Amigos, in the Madre de Dios region, Peru. File | Photo Credit: Reuters

Tropical birds, from kingfishers to wrens to warblers, are showing signs of mercury contamination as artisanal and small-scale gold mining operations reach deeper into jungles, finds a new research.

Birds living within 7 km (4 miles) 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 published on Tuesday in the journal Ecotoxicology.

A scientist takes a blood sample from a bird while researching for signs of mercury poisoning in animals at a makeshift medical clinic, at the Los Amigos Biological Station, in Peru. File

A scientist takes a blood sample from a bird while researching for signs of mercury poisoning in animals at a makeshift medical clinic, at the Los Amigos Biological Station, in Peru. File | Photo Credit: Reuters

"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 declining in 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," Mr. Sayers said.

Over a 17-year period ending in 2023, dozens of scientists collected thousands of feather, blood and tissue samples from 322 bird species across nine countries in Central and South America and the West Indies, creating the world's largest database to date on mercury concentrations in birds.

The research adds to a growing understanding of how mercury, which is used by gold miners to separate the precious metal from sediment, is impacting wildlife in the tropics.

Artisanal gold mining is often either carried out illegally in protected areas, or done informally outside reserves but without explicit government permission.

Earlier this year, Reuters reported for the first time that scientists were finding mammals, from titi monkeys to ocelots, showing signs of mercury contamination near a Peruvian gold mining hotspot.

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.

Birds are the "canary in the gold mine," Mr. Sayers said, as they are sensitive to mercury pollution and easily accessible, allowing scientists to take the temperature of overall ecosystem health.

A camp of informal gold miners is pictured in Los Amigos, in the Madre de Dios region, Peru. File

A camp of informal gold miners is pictured in Los Amigos, in the Madre de Dios region, Peru. File | Photo Credit: Reuters

The collected samples revealed some of the highest-ever recorded mercury concentrations in songbirds. Birds that ate meat or lived in aquatic habitats were also found to have the highest overall mercury levels.

Hotspots for mercury contamination included Madre de Dios, Peru, and Ayapel, Colombia — centres of artisanal gold mining.

Birds in central Belize also had high mercury concentrations, with scientists speculating it could be due to gaseous mercury emissions from local landfill incineration, or coal combustion in the surrounding region.

0 / 0
Sign in to unlock member-only benefits!
  • Access 10 free stories every month
  • Save stories to read later
  • Access to comment on every story
  • Sign-up/manage your newsletter subscriptions with a single click
  • Get notified by email for early access to discounts & offers on our products
Sign in

Comments

Comments have to be in English, and in full sentences. They cannot be abusive or personal. Please abide by our community guidelines for posting your comments.

We have migrated to a new commenting platform. If you are already a registered user of The Hindu and logged in, you may continue to engage with our articles. If you do not have an account please register and login to post comments. Users can access their older comments by logging into their accounts on Vuukle.