Fall's Journey South Update: October 9, 1998
Today's Report Includes:
They're On Their Way!
Loons are on the move, winging
their way from Canada and the northern states to the oceans. Juveniles are leaving and most adults are already
gone. Joe Kaplan and Keren Tischler, Journey North's loon experts, spent this spring, summer and fall studying
loons. Right now they're finishing up field work and getting ready to migrate themselves, all the way to Madagascar
for another research project, but Joe made time to talk to Journey North about some of the work they've done and
things they've learned this year.
Bands Aid Studies
Loons are banded at night, lured in with recordings. In fall and winter on
the ocean, scientists use loon hoot or wail calls.
Joe and Keren follow individual loons, recognized by their colored leg bands. Joe said banding work gets easier
every year, because most of the loons they're studying are now already banded.
Joe explained that in Seney National Wildlife Refuge in Michigan and Isle Royale in Lake Superior, loons enjoy
94% survivorship-that means a full 94% of adults survive from one year to the next. Pairs don't seem to stick together
through the winter (How
did they find out that pairs winter apart?) When the loons return in the spring, 10-15% switch mates or territories.
Overall about 85% return to the territory they were at in a previous year. Based on banding returns, biologists
estimate that 5% of adult loons return to the same territory for at least 30 years. This means young loons arriving
on the scene for the first time have a very hard time finding an open territory.
"Papa"-One Loon's Life and Death
Joe told us about one male loon, "Papa," who was banded at Seney in 1988-the first banded loon studied
under the North American Loon Biomonitoring Program. This year, 1998, Papa FINALLY managed a successful nesting.
It took him eleven seasons to work his way into an open territory--that's how tough the competition is! And poor
Papa won't return next year--he died and was eaten by an eagle. So next year another loon will finally get a chance
at a territory. Papa's genes will live on in the young that he produced--if one of them makes it to maturity and
nests, Papa will become "Grandpapa."
Copyright Woody Hagge
Through behavior studies of banded birds, Joe and Keren have been trying to find answers to several important questions
about loons. This year they've focused most of their work on Isle Royale, where they are researching how much kayaks,
canoes, and other boats disturb nesting loons. They're also analyzing blood and feather samples of birds on both
the Great Lakes and smaller lakes and then following the individual birds' behaviors to figure out how mercury
levels affect nesting success. For example, scientists know that swimming parents brood chicks on their backs less
when mercury levels are high. Is this because the chicks are less coordinated? Because the parents get confused?
No one knows--but Joe and Keren are trying to find out!
Copyright Woody Hagge
You Don't Have to Cry About It!
Right now, along the Atlantic and Pacific seaboards and in the Gulf of Mexico, loons are making a critical switchover.
Since early spring, they have been living in lakes and rivers, drinking freshwater and eating freshwater fish.
But the moment they plunge into the ocean for the winter, they must suddenly survive drinking saltwater and eating
salty fish. If their bodies don't adapt quickly, they will die. Fortunately, they have a salt gland between their
eyes that takes all the extra salt out of their blood. They get it out of their bodies by making VERY salty tears!
Range of the Common Loon
courtesy of the D. Bojar ('99) Geography Dept. Macalester College
Loons come to the oceans from all over Canada and the northern states. A scientist holding a loon caught on
the Atlantic Ocean can get an idea where it came from just by what it feels like! That's because the farther west
of the Atlantic a loon lives, the smaller it is. Which leads us to this week's
Challenge Question #6:
"The weight of adult male loons in Maine averages heavier than 6000 grams, while loons from Michigan and
Wisconsin average only about 4500 grams. Wings are about the same size on each. What might be one explanation for
that huge difference in body size?"
To Respond to Challenge Question # 6 please follow the
instructions at the end of this report.
Discussion of Challenge Question #5:
Why don't hurricanes hit the West Coast as they do the East and Gulf Coasts? Dan Mulhern of the US Fish and Wildlife
Service explains this very clearly: "Most hurricanes and tropical storms tend to track from east to west,
so hurricanes that develop in the Pacific rarely track toward the west coast of the U.S. and Canada. Rather, these
track towards Asia." Of course, as Robert M. Protz from West PA adds, "While it's true that most Eastern
Pacific tropical cyclones track away from the coast - west towards Asia, the reason that the rare ones that do
track more northerly towards California never make it that far is that they run into very cool waters from the
California Current, and that environment doesn't support the sustaining of the cyclone's energy cycle."
How to Respond to Today's Challenge Question:
1.Address an e-mail message to: firstname.lastname@example.org
2.In the Subject Line of your message write: Challenge Question # 6
3.In the body of the message, answer the Challenge Question.
The Next Journey South Update Will Be Posted on October 16, 1998
Copyright 1998 Journey North. All Rights Reserved.
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