Keeping an eye on mercury

Mercury kills, and its presence in the environment is an indicator of potential trouble on the horizon for all species, including humans. Anthony DePalma reports in the NYT on a study recently released by the BioDiversity Research Institute on increased levels of mercury in Bald Eagles in the Catskill Mountains region of New York.


We've known for quite a few years that mercury was a problem in the northeastern U.S. and southeastern Canada. Charlie Driscoll and his colleagues, working under the umbrella of the Hubbard Brook Research Foundation, reviewed the existing data on mercury deposition in the Northern Appalachian ecoregion and showed that mercury levels here routinely exceed human and wildlife health thresholds. Chris Rimmer, at the Vermont Center for Ecostudies, and his colleagues reported in the journal Ecotoxicology in 2005 that even an upland species like Bicknell's Thrush, which inhabits high elevation forests in the Northern Appalachians during the breeding season, has levels of mercury in its blood in excess of accepted health thresholds.

The presence of mercury in a species like Bicknell's Thrush is particularly disturbing. While still not acceptible, mercury in Bald Eagles is at least understandable. Ionic forms of mercury deposited in aquatic ecosystems are converted into methylmercury (a form that causes severe neurological damage and death) by bacteria; methylmercury is then bioaccumulated up through the aquatic food chain and eventually gets incorporated into the tissues of Bald Eagles, which eat a lot of fish.

But Bicknell's Thrush? Either this upland songbird eats far more aquatic insect larvae than previously understood (and methylmercury is bioaccumulating in these short-lived insects to a much greater extent than previously believed) or there are terrestrial pathways from ionic mercury to methylmercury that we don't fully understand, which means that more species are susceptible to mercury poisoning than we thought.

Either way, it's not good news. And neither is the fact that mercury levels are on the rise.

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Quote of the day

Much that is good and all that is evil has gathered itself up into the Western Gull. He is rather the handsomest of the blue-mantled Laridae, for the depth of color in the mantle, in sharp contrast with the snowy plumage of back and breast, gives him an appearance of sturdiness and quality which is not easily dispelled by subsequent knowledge of the black heart within. As a scavanger, the Western Gull is impeccable. Wielding the besom of hunger, he and his kind sweep the beaches clean and purge the water-front of all pollution. But a scavanger is not necessarily a good citizen. Call him a ghoul, rather, for the Western Gull is cruel of beak and bottomless of maw. Pity, with him, is a thing unknown; and when one of their own comrades dies, these feathered jackals fall upon him without compunction, a veritable Leichnamveranderungsgebrauchsgesellschaft. If he thus mistreats his own kind, be assured that this gull asks only two questions of any other living thing: First, "Am I hungry?" (Ans., "Yes.") Second, "Can I get away with it?" (Ans., "I'll try.")

William Leon Dawson, in Birds of California (1923)

Which reminds me of a poem I wrote once while waiting for a ferry in Australia ...

“First Precept of Food Webs”

Dark-eyed vulture with one question—
Do I have food?
In the eyes of the Great Spirit I am only that.
I am not yet edible,
and the vulture flies away.

Steve Trombulak (2000)

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A Year of Birding Strenuously

Yesterday marked a milestone for me: indeed, self-imposed and of no real consequence to what I do even today, but a milestone nonetheless. Yesterday, at 4:35 pm, in the dying light of a cold New England day on an obscure dirt road near my house, I saw a flock of eight Short-eared Owls hunting low over a hay field. I had gone out there on a tip from a fellow birder who posted on our state-wide birding discussion list (VTBIRD) that he had seen them there the day before as dusk was creeping in. I raised my binoculars to my eyes, hoping that I would find them before it became full-on dark, and I saw them in an instant. Graceful, quiet, impressive as hell, especially because of their (to me) surprising numbers. I watched them for about 30 minutes, never trying to get too close for fear that they would fly off to a different field. Eventually, even with the almost-full moon in the sky, it was too dark to see even their distinctive wing markings, so I called it a day and went home.



But as magnificent as they were -- and I cannot overstate just how magnificent they were -- that is not why yesterday was a milestone. Those Short-eared Owls represented the 150th bird species that I had seen this year in Addison County, where I live. I had successfully hit a target that I had set for myself at the beginning of the year: I wanted to see 150 species of birds in my local area this year.

There was nothing magical about the number 150. It seemed doable (with some attention and effort), I knew it was possible given the number of bird species that have been reported for the county over the last 10 years (courtesy of Vermont eBird), and I knew that there were plenty of other birders in this region who would probably see 150 species by May alone. But I knew that a target would be fun and keep me trying just a little bit harder (hence the whole "standing on the edge of a wind-swept hay field in the growing darkness of a mid-November dusk" episode), and based on my previous years of birding here I thought 150 seemed reasonable.

No, it wasn't the number. What to me was the most exciting is that I did it in my local area. In fact, for the first time ever, I spent ALL of my hard-core birding efforts only in a small area (about 800 square miles, which when you think about it is not all that large; it's a square just 28 miles on a side). For the first time ever, I purposefully chose not to burn fossil fuels driving to distant locations to see rare European or South American vagrants, not to try and be intimate with the natural history of an entire continent but rather only with the dirt roads, woodland stands, and muddy seeps around my neighborhood. Heck, I even ignored rarities reported from neighboring Vermont counties, sticking to my mantra: Think globally; Bird locally.

And I feel like I succeeded. Yes, I hit my target of 150 with 40 days to spare in the year -- I count my years from the Winter Solstice, not from the arbitrary assignment of January 1st in the Gregorian Calendar (about which I can write another time) -- but more importantly, I feel like I have regained an intimacy with my home landscape that no amount of natural history jet-setting could provide. I've had the privilege of seeing how different farmers time the harvest of their corn and hay, how the water levels in small no-name tributaries rise and fall, and how the light reflecting off of Lake Champlain changes week by week. I feel like I know this place better than ever before.

And I feel like I found, at least for now, a compromise between my awareness of our moral responsibility to care for the Earth in deed as well as in word and my desire to simply Get Out There and witness the Web of Life in action. I am better for it. And I can't wait until next year; 160 species, here I come!

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Winter birding

Few things get me more excited than being able to emerse myself in the rhythm of the year. Living in New England as I do, I am especially blessed with distinct seasons, each with their own characteristics. Friends who are less enamored of cold climates than I cannot understand how I can possibly live here, but in truth I love winter just as much as any other season. This is in part because the natural world takes on a character all of its own. This is especially true for the birds here. Rather than being devoid of birds as most of our summer residents head south to warmer climates, New England and most of the northern tier of states become the winter home for a wide assortment of birds that move down here from Canada.

But no two years are ever alike. Some years, we see few of these winter migrants; in other years, they are thick as warblers in the summer. Which is why I was so please to see this posting on the VTBIRD discussion list the other day ...

"As many already know PINE SISKINS are waging a very large irruption from Illinois, Missouri, Ohio, Ontario, and from Maine south to Georgia already.

"Certainly an invasion of this size has not been seen in many years. An impressive and widespread WHITE-WINGED CROSSBILL invasion has also materialized with modest numbers reported at many of the same NE areas as the siskins with a few RED CROSSBILLS mixed in here and there as well.

"PURPLE FINCHES and AMERICAN GOLDFINCHES are also moving in these same areas in good numbers.

"COMMON REDPOLLS also appear to be starting to move in large numbers as reported from Quebec and in lesser numbers at Whitefish Pt. in Michigan.

PINE GROSBEAKS and EVENING GROSBEAKS are showing signs of making at least a small push too."

Let it snow, let it snow, let it snow! My back yard will be coming to life again, and I get to play one more time with the Rhythm of Life.

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