Loons Sound Alarm on Mercury Poisoning

  • Breakfast for loon chick. Loons have survived, and thrived, through multiple threats. Now mercury is a problem for the species. Photo: Some rights reserved, Keith Carver,Creative Commons

September 6, 2013
By David Sommerstein

I like loons.  I’m sure you do, too.  When you hear their call echo across the water, you feel special. But it’s a totally different feeling when you’re in a boat, someone swoops a net into New York's First Lake, scoops up a loon chick, and plops it in your lap. It's such a little thing.

Nina Schoch runs the Biodiversity Research Institute’s Adirondack Center for Loon Conservation, "Chicks are kind of like owls, they like to have their heads rubbed and it will put them to sleep and keep them calm," she says.

Schoch's team has banded and monitored more 200 loons in the park since 1998.

Banding loons is really a labor of love.  Labor because you have to do it at night.  It can get cold and rainy, even in summer.  The loons don’t want to be caught.  So you trick them.  You play an electronic call to lure them close, shine a floodlight in their eyes to blind them, and Schoch says you still might miss.

"It’s almost magical being out with them, but it is very frustrating when they come so close to the boat and you think you have them in the net and the net comes up empty," she says.

The love, of course, is why these researchers have dedicated large chunks of their lives to the iconic birds.

Loon sentinel Gary Lee holds the net like a staff and scans the water’s surface. 

"I mean, I talk to all my birds.  I watch 22 lakes and I talk to all the birds.  I go in the same canoe every time, same clothes.  They know me.  They talk to me when I go out there," Lee says.

Lee and Schoch worry about loons like parents, even though the birds are thriving these days.  Lee says he saw kids on jet-skis buzzing loons. One loon on this lake has a broken leg from a motorboat.  Lead sinkers and other fishing tackle are poisoning birds. But Nina Schoch says the biggest threat is mercury, "21percent of the males and 8 percent of the females have mercury levels high enough to impact their reproductive success."

Schoch and her team observed those high mercury birds, and what they saw alarmed them. Mercury is a neurotoxin, so it makes them depressed and lethargic and they don’t have the energy to defend their territories well, they don’t get up on the nests as much. They just don’t have the energy like they normally would to care for the nest and the chicks.

A study released last summer uses Schoch’s data to quantify the effects of mercury.   It found male loons with high levels of mercury in their blood produce 56 percent fewer chicks than healthy loons.  Female loons produce 32 percent fewer.

Study co-author David Evers says mercury is dampening the overall good news of the loon’s rebound over the last three decades. "So there’s a recovery going on now across the region, but it would have been stronger recovery, and I still wonder will that recovery continue if mercury is a stressor," Evers says.

What happens when other stressors come into play? Evers says the implications go beyond loons.  "They’re a good indicator species.  They eat at the top of the food chain and live up to 30 years," he says. "If it’s affecting loons, it’s affecting other birds that are eating fish regularly from those same lakes, and I think you can easily make that next step that that can impact our own health, especially if we’re regularly catching and eating fish from those same lakes."

The mercury comes predominantly from coal-fired power plants in the Midwest. Clarkson University professor Tom Holsen has been studying mercury in the Adirondacks for more than a decade. "Prevailing winds, as we all know who live here, are from the southwest, and that’s the exact direction of the coal-fired power plants," he says.

One year ago, the Environmental Protection Agency finalized new rules for mercury emissions.  And already dozens of coal-fired units are being shut down because they’re too costly to retrofit.  Utilities say that will mean higher electricity prices.  But Holsen says it should also lower mercury levels in Adirondack lakes. "Now attention is turning to global mercury levels as coal continues to power Asia’s economies," he says.  A summit in Geneva will try to hammer out a treaty to reduce mercury emissions worldwide.

You could argue that the headline here should be more of a good news story.  The number of breeding loon pairs in the Adirondacks is estimated to have doubled since the 1980s.  Stricter rules appear likely to reduce mercury contamination in the park.

Still, researcher David Evers argues concern for loons and funding for more study has to continue. "We have reversed the tide that has happened a century ago, he says. "That’s a great thing that we should be happy about.  I think we can do more. And I think some things like mercury get in the way."

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