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Loon Migration Update: April 6, 2000
Today's Report Includes:
- Loons Are On The Move!
- Nesting, or Just Passing Through? Challenge Question #13
- A Ton of Fish
- Challenge Question #14
- The Loon Food Chain
- Try This! Back Into Balance
- Looney Tunes in the Air
- Loon #2539, Where Are You? Answers to CQs #6, #7, #8
- Who Needs Wet Suits? Discussion of CQs #9, #10, #11
- Answers Lead to More Questions: Response to Challenge Question #12
Loons Are On The Move!
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As you make your migration map today, consider why the loons are appearing where they are, WHEN they are. Also
consider what they are doing...
Nesting, or Just Passing Through?
Good question! Loon migration is extremely variable, but we know some things for certain. Loons are in their new plumage when they leave their wintering grounds. They leave as inland lakes open up, first gravitating to the large, open Great Lakes. When ice on their nesting lake holds them back, loons often end up staying on a lake in collections. But when ice isn't a factor, loons are often seen as single birds. How do you explain these sightings?
Thomas Cooper and seventh graders from Gowanda Central School in Gowanda, NY (42.3602, -79.2709) reported:
"Have seen a single loon for four days straight. Last year we had 8 loons for a week." (gr7science@gcsd.com)
Sharyn Chiavaroli from Airline Community School in Aurora, ME reported:
"Yesterday the ice went out on Grahm Lake (44.66N, -68.39W) and now the lake is full of loons. Almost 20 have been spotted. Tonight the air is full of their calls."
After reading these sightings, send us your answer to:
Challenge Question #13:
"What clues can you look for to tell whether loons are just passing through, or might be staying to nest?"
(To respond to this question, please follow the instructions
below.)
A Ton of Fish
The loons arriving on their home lakes will certainly be hungry. An ornithologist calculated that it takes 2,000 pounds of fish to feed a pair of loons and their chicks over a single breeding season! Loons that are nearly full-grown eat about 22% of their total body weight in food every day. Tiny, fast-growing chicks eat more like 40% of their weight every day!
Challenge Question #14:
"If you wanted to find out how much the average student in your class eats as a percent of body weight per day, what would you need to do? Design and try the experiment. How does YOUR rate of food consumption compare with that of loons?"
(To respond to this question, please follow the instructions
below.)
The Loon Food Chain
If you follow a loon's food chain, what will you find? What does the sun have to do with it? For more about the amount and type of food loons eat, reproducible illustrations to help you create the food chain, and some mind-bending questions, see:
- A Ton of Fish: The Loon Food Chain
Try This! Back Into Balance
Loon bodies are streamlined for fast underwater swimming, which makes them such good hunters and divers. But this comes at a cost. A loon's legs are much farther back on its body than its center of mass, or where weight and balance come together. To understand "center of mass", get some modeling clay and try this experiment:
1. Use most of your clay to form a loon-like body shape.
2. Then form two balls to represent the legs. Stick these two balls in the middle and try to balance your bird.
3. When you've succeeded, move the balls of clay back a bit, and try to balance the bird again.
Does it help if you change how the body is oriented? Keep moving the clay back little by little, making any changes that help to balance the body each time. What things affect the center of mass?
Looney Tunes in the Air
Journey North's Mary Hosier welcomed her first loons on March 29:
"Heard a strange but familiar call this morning just after sunrise. Next, I waited and was rewarded with the sight of 2 loons flying in the near distance. Finally, as they passed over, they sounded another call before heading on toward Bald Eagle Lake (45.09N, -93.00W).
Would you know what a loon looks and sounds like when it gets back to your area? Hear what Mary heard, learn what the calls mean, and listen for loons in your area! Remember to report your first loon to Journey North!
Loon #2539, Where Are You? Answers to CQs #6, #7, #8
Challenge Question #6 asked: "What was the total number of days Loon #2539 traveled?"
Answer: 25 days between November 2 and November 26, 1998.
Challenge Question #7 asked: "What was the total distance Loon #2539 traveled?" Here's the daily progress report, with the totals at the bottom:
Calculated Loon Migration distances for Loon #2539:
11/2/98 - 11/5/98: 68.32 km 42.46 mi
11/5/98 - 11/9/98: 161.38 km 100.30 mi
11/9/98 - 11/11/98: 370.99 km 230.57 mi
11/11/98 - 11/13/98: 76.12 km 47.31 mi
11/13/98 - 11/15/98: 126.25 km 78.46 mi
11/15/98 - 11/18/98: 10.13 km 6.30 mi
11/18/98 - 11/20/98: 5.18 km 3.22 mi
11/20/98 - 11/24/98: 91.49 km 56.86 mi
11/24/98 - 11/26/98: 623.02 km 387.21 mi
11/26/98 - 11/28/98: 651.25 km 404.75 mi
TOTAL 2184.13 km OR 1357.44 mi
Challenge Question #8 asked: "What was the average number of miles (or km) Loon #2539 traveled per day?" Divide the total number of miles (or km) by 25 days traveled for the answer: 87.365 km or 54.297 miles.
Who Needs Wet Suits With Feathers Like These? Discussion of CQs #9, #10, #11
In CQ #9, we asked: "How do you think a loon's beak, eyes, legs, and feet stay warm when exposed to cold water?" Only an expert could have known these answers, and we thank Laura Erickson for responding! Laura explains:
"The loon's beak is made of the same kind of tissue as our fingernails, without a blood supply that could get cooled by the air and then travel to the rest of the loon's body. No matter how cold the beak gets, the rest of the loon can stay warm. The legs and feet have a much smaller blood flow than our legs and feet, but still need enough blood to power the muscles that help it swim. Blood flowing from the cold feet back up into the warm body gets heated before it reaches the body because it travels in vessels right next to the hot blood traveling down to the feet from the body. This is called a "double shunt system."
"Loon eyes don't turn nearly as much as ours do, so their eyelids don't expose as much of their eyes. That's why you don't see more than the iris and pupil on a bird's eye. Minimizing the exposed part of the eye helps prevent it from drying out when a bird is flying, and from losing too much body heat. And for even more help, birds have an inner eyelid called the nictitating membrane. They can swim or fly with this inner eyelid closed part of the time, and still see because it's transparent!"
Challenge Question #10 focused on feathers: "How do contour feathers keep the body inside so dry?"
Laura Erickson gave us the details. "Water molecules are attracted to other water molecules--that's why water forms droplets rather than sheeting away on most surfaces. Contour feathers are so tightly fitted together that drops of water can't squeeze between. To help even more, loons have an oil gland on the base of their tail. It looks like a funny pimple, and when they squeeze it or rub it with their bill, small amounts of oil come out, which they wipe on their outer feathers to make them more waterproof."
And Challenge Question #11: "What's the total number of feathers you think a loon has on its body?"
"Back in 1936 and 1949," wrote Laura Erickson, "two ornithologists actually counted every contour feather on several birds. The smallest number was on the Ruby-throated Hummingbird, who had 940. The most was on a Tundra Swan, with 25,216. We don't know of anyone who counted all the feathers on a loon, but we'd guess they have somewhere between 18,000 and 20,000."
Answers Lead to More Questions: Response to Challenge Question #12
Last time we asked: "Why don't loons winter on southern lakes that are open and have plenty of fish?"
Rebecca and Cameron Zacher think it's because "they return to where they were hatched, which is in the north." (zack@alaska.net)
That's part of the answer! The other part concerns what loons need for survival: VERY clear, deep, open water for diving and catching fish. Loons leave their breeding lakes because they freeze up, but there are good reasons why they don't head for warmer southern lakes. Mainly, it's because the water in those lakes is too warm, or too shallow and murky for diving and hunting. And preying alligators may lurk in many of those lakes! The ocean is the right place for loons in winter when their breeding lakes are frozen.
How to Respond to Today's Challenge Questions:
Please answer ONLY ONE question in each e-mail message!
1. Address an e-mail message to: jn-challenge-loon@learner.org
2. In the Subject Line of your message write: Challenge Question #13 (or #14).
3. In the body of your message, give your answer to ONE question.
The Next Loon Migration Update Will be Posted on April 20, 2000.
Copyright 1999 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form
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