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Tuesday, January 12, 1999
Rising mercury hurts loons
Tailpipe of North America receives `warning'
By David Swick
THE CRY OF LOONS, a new report by two Acadia
University biologists suggests, might be a cry for help.
Graduate student Joe Nocera and professor Dr. Phil Taylor say loon
chicks in Kejimkujik National Park and southern New Brunswick are
demonstrating unusual behaviour. It's a sign, they believe,
mercury poisoning is impairing the loons' nerve functioning.
"This is a warning," Nocera says. "It's not loon armageddon - yet.
A lot depends on where the mercury is coming from. If it's in
natural bedrock and leaching through, that's one thing. If it's
coming through the atmosphere then there's lots to do."
Excessive preeners
Three years ago scientists discovered Keji loons have North
America's highest recorded mercury levels. Now, in a report
published in Conservation Ecology, Nocera and Taylor say loon
chicks in Keji and New Brunswick's Lepreau watershed are engaging
in excessive preening, and don't ride on their parents' backs so
often.
Riding on back protects the chicks from predators; excessive
preening wastes valuable energy and so makes the young more
vulnerable, too. Chicks with lower levels of mercury, a potent
nerve poison, have not changed their behaviour.
Coal-fired power plants, incinerators, and other industrial
concerns puff mercury into the atmosphere. A recent report in
Environmental Toxicology and Chemistry, Nocera said, showed the
level of mercury in loon blood increases from west to east across
the continent. Toxins are deposited in a similar pattern.
Nova Scotia, Nocera said, is the tailpipe of North America.
"We get all these atmospheric wind patterns that merge on Nova
Scotia. When they cross Fundy they cool down, and precipitate
here. That's why we get more precipitation than New Brunswick.
"We can't point fingers, but all the evidence is pointing to a
manmade source."
Scientists studying pollution find loons especially interesting
because loons are a top predator in the aquatic food chain, and
absorb mercury from eating fish.
This winter Nocera is finishing three years of graduate study. His
last two summers were spent on the shores of Keji lakes, or lakes
in the Lepreau watershed, watching loons from breakfast to
sundown. Findings for New Brunswick are discouraging, too, but not
as bad as Keji.
A Connecticut native, Nocera came to Nova Scotia to work on loon
research. The birds had fled Connecticut - and much of New England
- before he grew up. He heard his first loon in Maine in the early
'90s - and that was one crying from the ocean. He'd never seen a
loon on freshwater before coming to Nova Scotia.
The bird has three haunting, famous cries: the sad wail; the
tremolo, a staccato that crescendos and then drops; and the yodel
(made only by males). But in total, loons make five calls. "There
are also the hoot and the mew," Nocera said, "very soft cat-like
calls used only in family units. You have to be really close to
hear them."
It's all in the air flow
Loons cry by contracting muscles to push air through a
complicated, multi-chambered windpipe.
"We speak by contracting the larynx, which is like a knot, and
controlling air flow through one channel. All birds have a syrinx
instead of a larynx. It vibrates differently, and has four - a few
birds even have eight - caverns inside it.
"When they contract muscle, the syrinx vibrates in different
patterns."
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References
0. http://www.hfxnews.southam.ca/Perspective/Swick.html
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