Researchers in the United States have traced a sharp rise in mercury pollution affecting many tropical birds to gold mining activities. The findings were published in the scientific journal Ecotoxicology, highlighting a connection between mining practices and toxic metal exposure in wildlife and ecosystems.
In a broad survey, scientists examined 2,316 blood and feather samples from 322 bird species across nine countries in Central and South America and the Caribbean. The results showed mercury concentrations among the highest ever recorded in songbirds, underscoring how widespread and serious the contamination is. A striking example reported by the team described a green kingfisher carrying mercury levels roughly 30 times above what is considered safe for birds, illustrating the extreme impact of environmental exposure on individual animals.
The researchers point to gold mining as a central source of this pollution. Mercury is used in artisanal and small-scale mining to extract tiny gold particles from soil and sediment. There, mercury binds to gold, forming an amalgam. When heated to release the gold, mercury vapor and liquid mercury escape into the surrounding air, water, and soil, creating a broad environmental footprint that affects local food chains and habitats.
Beyond direct mining sites, other land-use changes contribute to the problem. Deforestation for agricultural purposes, often achieved by burning vegetation, releases mercury held in the ecosystem, adding to the atmospheric load and facilitating its spread across wider areas. The spread of mercury is not limited to one set of organisms; biologists detected elevated levels in birds of prey and aquatic species as well, indicating a food-web-wide exposure that can ripple through ecosystems.
Predatory birds—those that feed on other animals—show heightened sensitivity to mercury because they accumulate it through the flesh of their prey. This biomagnification means that top predators can carry higher concentrations than organisms lower in the food chain, with potential consequences for their health, behavior, and reproductive success. The same mechanism can affect amphibians, fish, and other wildlife that rely on aquatic or semi-aquatic environments where mercury accumulates in sediment and water bodies.
From a health perspective, mercury pollution poses risks beyond wildlife. Scientists caution that contaminated ecosystems can translate into human health concerns, particularly for communities relying on local fish and game for sustenance. Mercury exposure weakens immune defenses in animals, increasing vulnerability to pathogens and diseases. In some cases, these health risks have implications for people who might be exposed through consumption of contaminated wildlife or through environmental contact in affected regions.
To put the situation in perspective, current research emphasizes the outsized role of artisanal and small-scale gold mining in global mercury emissions. This form of mining remains a major driver of pollution, contributing a substantial share of human-caused mercury release into the environment. The ongoing challenge is to balance the economic importance of small-scale mining with the urgent need to reduce mercury exposure for both wildlife and humans in affected regions. Scientists advocate for strategies that limit mercury use, promote safer mining techniques, and protect ecosystems from the cascading effects of contamination.
In exploring these dynamics, researchers also acknowledge the interconnectedness of habitat disturbance, pollution, and climate-related stressors. Mercury is persistent in the environment, and its pathways—from soil and sediment into water bodies and then into the organisms that inhabit those waters—highlight the need for comprehensive monitoring and community engagement. The goal is to minimize harm while supporting livelihoods that depend on natural resources, all within a framework of science-based policy and stewardship. Future work will continue to map exposure across species and geographies, refine risk assessments, and identify practical interventions that reduce mercury release and exposure without compromising local economies and nutrition.
Overall, the emerging picture is clear: mercury pollution from gold mining and related land-use changes poses a real threat to tropical birds, aquatic life, and human communities connected to these ecosystems. By strengthening regulations, adopting safer practices, and enhancing monitoring efforts, it is possible to curb the spread of mercury, protect biodiversity, and safeguard public health for generations to come. (Attribution: Ecotoxicology study and related field research.)
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