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Nesting Loons Help Researchers Track Toxins



The cry of the loon is one of the most evocative sounds of summer on lakes across the northern U.S. Beyond providing a soundtrack to northern summers, it turns out that loons are good indicators of the level of mercury in the environment. That's the analysis of a group of scientists who have taken to the waters of Maine for what's believed to be the longest-running loon monitoring study in North America. Maine Public Radio's Susan Sharon accompanied them on a nighttime mission, putting bands on loons.

SUSAN SHARON, BYLINE: This is Aziscohos Lake on the Maine/New Hampshire border. It's home to about 20 pairs of nesting loons and their young. During this time of year, staff members with the Biodiversity Research Institute maneuver in and out of its quiet, dark coves several times a week.

MISTY LIBBY: It's not a vacation out here. People think we kayak and we spend all our time on the lake, but it's hard work, and it's windy, and there's bugs.

SHARON: Misty Libby is a field technician who has dressed for the occasion.

LIBBY: I have thermal underwear, top and bottom, some Dickies, some rain pants, two old sweaters, and a hat.

SHARON: Before setting off in a small motor boat, we get some final safety instructions about handling the birds.

MICHAEL CHICKERING: When we get a loon in the boat, the most important thing you want to pay attention to is the head.

SHARON: Michael Chickering is the Maine Loon Program Coordinator.

CHICKERING: We wrap the head in a towel, but they do have a very sharp, pointy bill. But if you do get bit, don't pull away. It's like getting grabbed by four knives, and they'll cut you really deep. So if they grab your hand or anything, say something. You know, we'll come over, we'll open the bill up and we'll remove your hand.


SHARON: Loons typically weigh between 12 and 15 pounds. They have velvet black heads, black-and-white patterned wings, and distinctive red eyes. Chickering patrols the lake, playing a series of pre-recorded loon calls to try to get them to respond. The work is done in the pitch black with a three-foot net and a spotlight that temporarily blinds the birds and discourages them from quickly diving out of reach.


SHARON: The actual captures happen suddenly, without warning.

CHICKERING: I'll have to check the combination, but this is a fairly old bird, just from the looks of the band.

SHARON: With a loon securely held like a football, and illuminated only by their headlamps, Chickering and his team weigh and measure the bird. Then they take blood and feather samples. Test results have shown that large amounts of mercury cause loons to become lethargic and discourage them from properly caring for their young. But the concern is not for loons alone.

LIBBY: People eat fish, these guys eat fish, and we can study the accumulation of mercury and relate it to people.

SHARON: By 1:00 a.m., the crew has worked up three loons, including a young chick. Over the past 25 years, the Biodiversity Research Institute has captured and banded more than 450 birds in Western Maine. They're telling scientists about how their world intersects with ours. For NPR News, I'm Susan Sharon. Transcript provided by NPR, Copyright NPR.