ife. We already know that mercury can be a big problem in human health. This research establishes that the effects of mercury are happening all over the planet, all over many habitat types, to vertebrate species other than ourselves. So people should be concerned about these effects, because there’s a link between human health and ecosystem health.
Q. Back to the science of this. How the heck do you measure mercury in a bird population, anyway?
Evers: It’s actually very simple and straightforward. There are nice and easy ways to capture and/or take samples from an individual bird that are quick and are non-harmful to the bird and do very little disruption to its routine, other than just having it in a net or hand for a half hour or so. We take a blood sample — just a drop does the trick. We also can take a feather sample, which gives us more of a long-term picture of how much mercury has come into that individual over time.
Q. But how do you disentangle the effects of mercury on birds and bats from other factors? How do you know that it’s mercury that is causing the decline of the wood thrush or the little brown bat?
Evers: It’s a question we’re still studying. There are multiple stressors at play for many species and habitats, and as conservation biologists, we are trying to understand those. We want to provide scientific information to landscape managers and policymakers, so we will have these birds around for a few more hundred years at least.
Take the olive-sided flycatcher. In the last four years, it’s declined by 80 percent, so 80 percent of this population is gone in comparison to four years ago. It’s a bird that lives in bogs. Bogs are known to have high methylation rates of mercury, but they are not well-studied as a habitat whatsoever. Neither is the olive-sided flycatcher. So here you have a species in a habitat that I think is at great risk to mercury as a potential driver and a primary stressor for why this decline is happening. Mercury is an omnipresent stressor, but the question is always: Where is it a primary stressor?
Tear: I’d also add that, in some places where birds are declining, there has been no obvious habitat change, and many people think of the challenges as being primarily habitat loss, but we certainly know that, for example, some species like the wood thrush within the Adirondack Park, there are fewer wood thrush today than there were 20 years ago. They’re still there, but there aren’t as many. The question is why, and this is part of the disentangling of those different stressors that Dave is referring to.
Q. Is there any relationship between mercury emissions and greenhouse-gas emissions? Is there a climate change connection?
Tear: Well, many of the greenhouse gases like carbon dioxides and other air pollutants — such as nitrogen and sulfur, which cause acid rain, and mercury, which brings us this neurotoxic rain — come from power plants, and all of these air pollutants have negative impacts on our environment. Our research shows that we should be factoring in these ecological impacts when we consider the cost and benefits of regulatory programs such as the recent Mercury and Air Toxics Standards Rule. But so far, estimating the ecological impact of these air pollutants that are coming from similar sources as CO2 has not been done.
Evers: Climate change might also be causing great mercury methylation rates into ecosystems or even remobilizing mercury that was stored in the system. For instance, forest fires have become more predominant because of climate change in some parts of the country — and those forests hold a lot of legacy mercury in their systems, which can be released quite rapidly with a fire. Greater storm intensity and frequency could be increasing deposition of mercury from the global atmospheric pool to landscapes below. Increased wetting and drying cycles could be another factor in greater mercury methylation.
Q. It sounds dire. So what can anyone do?
Tear: First, while we need more research on this, there are definitely landscape and wildlife management actions that might h