Mercury in Birds and Bats

I want to highlight this research report for a couple of reasons.   First, it’s a summary of a lot of research on birds and bats–and it is alarming.  Major findings include:

• Current environmental mercury loads have the ability to significantly reduce reproductive success in several songbird species of conservation concern in the northeastern U.S. including the saltmarsh sparrow and rusty blackbird.
• Bats also build up significant body burdens of mercury;  individuals from multiple species from all 10 areas sampled exceeded the subclinical threshold for changes to neurochemistry.
• Mercury loading in songbirds is not only restricted during the breeding season; some species, such as the northern waterthrush, build up high levels of mercury during migration and in tropical wintering areas

Basically, this expands what we know about the dangers of biomagnification out into song birds and bats.  I’ve written about some of the research this report is based on before.

From an interview with an author:

“It is a game-changing paradigm shift,’’ Evers said. “For years, we’ve understood the notion that birds like an eagle can obtain toxins by eating a bass, which has eaten a perch, and the perch has eaten a fly. Now we understand the same kind of analogy can be applied to a water thrush, which eats a spider, which has eaten a smaller spider, which has eaten a fly.’’

The other reason I want to point you at this is because it’s a great example of how to produce a report on complex research and make it really accessible.  They don’t just have data; they have information on how to interpret the graphs.

The PDF report itself is beautiful to look at, and focuses on specific actions/conclusions that can be drawn from the data.  It’s a report that I could hand to any of my non-scientist coworkers and be confident they could read it and understand it.  The PDF is presented within the context of a page with lots of supplemental info, including jpgs of some of the figures.  This makes it easy for journalists to build a story.

A thermometer is used to indicate risk to certain species–which cleverly uses something commonly associated with Mercury, but also something a lay-person knows how to interpret without a lot of special background knowledge.

Lastly, they cited their research through the report in ways that let you look up the original research, but that doesn’t detract from your reading.  It makes a powerful case that we need to really start paying attention to the mercury in our environment–because it’s not just the birds that are exposed.

Additional Reading:

• Aquatic mercury in food webs
• USGS: Mercury in the Environment
• Game Changers: a report on how global warming and toxins might change hunting and fishing.
• EPA advisories on which states have fish too contaminated to eat