Common Loon Common Loon
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Loon Migration Update: March 22, 2001

Today's Report Includes:

On the Mark, Get Set, GO!
Unlike racehorses, loons don't have to wait for a "starting gun" in spring to signal them that it's time to move. Some of them have already started! By the time our next map appears on April 5, there should be a LOT of loons moving--and some already reaching the finish line! Loons can easily fly about 55-60 miles per hour (one being chased by an airplane once reached 100 miles per hour)! Flying several hours a day at a normal, steady speed, it doesn't take them long to reach their northern lakes.

Challenge Question #7:
"What are some of the advantages and disadvantages of being among the FIRST loons to migrate? What are some of the advantages and disadvantages of being among the LAST loons to migrate?"

(To respond to this question, please follow the instructions below.)

Some Sights and Highlights
Our farthest north inland sighting came from Madison, WI, where the very first common loon was seen on Lake Monona March 19. It's interesting to note that a power plant discharges heated water into this lake, resulting in earlier ice out. (Loons sometimes return to their breeding lakes within hours of ice-out!) Last year we received this observation: "Common Loon seen 4 PM March 18th on Monona Bay, a part of west area Lake Monona. This is the earliest I have ever seen one here since keeping records back to 1985." Now we're curious! Can loons wintering in the south time their migration to arrive on open lakes? Can they use weather as a timing tip? Stay tuned!

Biologist Kate Taylor, who coordinates a network of observers across the state of New Hampshire, writes: "Nothing to report from inland NH yet. We're still heavily snowed in, with another Nor'easter bearing down on us for tomorrow. We should start seeing loons along the rivers in the next couple of weeks, just waiting for ice-out. But I do have one interesting loon sighting for you. We banded a loon on Spectacle Pond, Enfield, NH in 1998. That loon was first seen in early March this year, off the coast along the Rhode Island/Connecticut border. It's still there, according to our observer."

Several other observations support what we know about how loons time their migration after their molt, which means growing a whole new set of flight feathers before their migration back to their breeding grounds. (You may not have thought about it, but feathers get worn out, frayed and weakened. That's why loons grow new ones every year.)

Plymouth, MA
"After the Nor'easter that blew through here the last couple days, I went to the shore today to about 4 locations. In all I saw 62 Common loons. Half were in basic plumage, the others were in partial breeding plumage, a couple were in 90% breeding/alternate plumage."

Vantage, WA
"Two Common Loons sighted on the Columbia River by Vantage, WA. They were in breeding plumage, diving and feeding along the bridge along I-90. Most of the lakes along I-90 and into Northwest Washington are still frozen."

Feather Wet Suits

Photo: Woody Hagge

This week's observations remind us that loons feed in cold areas of the ocean, where food is most abundant, and return to northern lakes almost immediately after the ice goes out--when the lake water temperatures are barely above freezing. A loon whose skin came in contact with that frigid water would quickly die of hypothermia. Fortunately, loons can keep their skin dry even when diving as deep as 60 meters down. How? Their feathers! Although the loon's skin is protected by feathers, its beak, eyes, legs, and feet are bare. So how do loons keep those body parts warm? Read more about how loons keep warm here:

Then come back and answer:

Challenge Question #8:
"How do a loon's beak, eyes, legs, and feet stay warm when exposed to cold water?"

(To respond to this question, please follow the instructions below.)

Juvenile Loons: Discussion of Challenge Question #5
Last time we asked this question about the young loon we tracked on its first migration to Florida's Gulf Coast: "How do we know juvenile Loon #15746 won't come back this spring?"

Loons generally stay on saltwater until age three or older. Exceptions can be found in nature, but it isn't common for young loons to migrate.

That's just one difference between young loons and older ones. Another difference is their timing for growing new feathers. Older adult loons grow new feathers in February and March. They molt their body feathers and their primary wing feathers, which are the ones most critical for flight. Fresh new feathers in February and March come just in time for the loons' journey north. Those fresh feathers will last for almost a year--through this spring and summer as they nest and rear their babies, all the way through their migration back to the ocean in the fall, and even through the early part of the next winter.

Last year's baby loons keep their old flight feathers until much later, not molting until late May or early June. With their old feathers, they are simply unable to migrate with the older birds. Two-year-old birds also molt late, though not as late as one-year-olds, and three-year-olds molt a bit later than four-year-olds. This means that almost all the birds that reach the north first are older, experienced birds that have the best chance of successfully breeding. Fortunately, most of the loons under age 3 or 4 stay on the ocean and don't even TRY to migrate.

Challenge Question #9:
"What advantages can you list for loons to molt on the ocean instead of on their summer lakes?"

(To respond to this question, please follow the instructions below.)

Life on the Ocean
Loons don't breed while they are living in the ocean. So what do they do? They spend their days feeding and preening, sleeping and resting, and watching out for sharks, seals, and other predators. They won't have to worry about sharks and seals on their northern lakes, but as young loons grow more experienced at dealing with these dangers, they grow more wary in general. This wariness will improve their chances of raising babies successfully when they finally do migrate, set up territories, and start nesting.

Q and A With Kevin Kenow

Radiomarked Juvenile Common Loon
Photo Courtesy K.P. Kenow, USGS

Juvenile Loon #15746's PTT raised this question with one class:

Q: Dear Dr. Kenow,
We have read the additional information about the PTT and how it has been attached to loons and other birds surgically, but how is infection prevented at the site of the implant?

Sincerely,
Students at Mt. Olive Middle School, Budd Lake New Jersey

A: "Great question," responded Kevin Kenow. "Transmitter implant surgery is conducted in as aseptic conditions as possible to limit infection. The transmitters and surgical equipment is cold sterilized in disinfectant and the surgeon wears surgical gloves and mask during the procedure. The passage of the antenna through the skin provides a potential conduit for infectious agents. To resolve this problem, we us a polyurethane catheter to provide a pathway for the antenna to follow. The catheter fits tightly over the antenna to provide an internal seal. A Dacron cuff around the outside of the catheter provides a substrate into which tissue from the skin can grow. The resulting integration of tissue with the catheter prevents migration of infectious agents beneath the skin."

Can You Identify a Loon by its Tracks?
Another student sent us this interesting question about loons: "How far apart are their prints when they walk? Do you know?"

We asked bird expert Laura Erickson, who agreed that loons are famously clumsy on land. Laura replied, "But interestingly, loons sometimes DO at least try to walk on land. If you actually saw loon prints, they'd be webbed feet (a bit bigger than most ducks--more like goose-sized), with very short strides between, and usually the mud would be all messed up between them because the loon would have to scooch along, flopping on its belly quite a bit. BUT Judith McIntyre, one of the world's most renowned authorities on loons, had a loon that she took on "walks" down to a river while she was rehabbing it. She'd put a dog harness on it and use a fishing line and reel for the leash. The bird would "run" up and down a hill in her yard leading down to the river, and apparently became rather adept at it." It seems there are always exceptions in nature!

Try This! Back Into Balance
The footprint question reminds us that 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:
  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?

Comparing Migrations: Answers for Challenge Question #3
Last time we asked you to compare the migrations of two different loons tracked by satellite telemetry. The question called for some mighty math calculations: "What is the average distance traveled per day by Loon #2539? Loon #15746?"
  • Loon #2539: Loon #2539 traveled 25 days between November 2 and November 26, 1998. Average distance traveled per day was 87 km or 54 miles.

  • Loon #15746: Loon #15746 traveled 13 days between November 16 and 28. Average distance traveled per day was 157 km or 97 miles.

When comparing the maps and data, did you notice that adult common loon #2539 from 1998 exhibited a completely different scenario from juvenile loon #15746? Loon #2539 stayed in a relatively small area near Pensacola, Florida. Loon #15746 stayed three days on a lake in Gainesville, Florida and then ranged widely on the ocean.

Fantastic Flyer: Answers to Challenge Question #4
Kevin Kenow provided numbers that would help you answer this question: "What was Loon #15746's approximate speed on the first leg of the trip? The second leg of the trip? The full trip?"

Here are the answers, and another question: Did this loon migrate by day or by night?
Trip Began Ended Time Distance
(km)		 Speed
(kph)		 Distance
(mi)		 Speed
(mph)
1st Leg 12:40 15:38 2.97 hrs 325.47 109.58 202.24 68.09
2nd Leg 15:38 18:07 2.48 hrs 211.48 85.08 131.41 52.99
Full Trip 12:40 18:07 5.45 hrs 536.95 98.52 333.65 61.22

Why the Ocean? Discussion of Challenge Question #6
"Why don't loons winter on southern lakes that have plenty of fish and no frozen water?"

Loons leave their breeding lakes because they freeze up, but there are good reasons why they don't head for warmer southern lakes. The answer concerns what loons need for survival: VERY clear, deep, open water for diving and catching fish. The water in unfrozen southern 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.

Look and Listen for Loons

Report the first Loon you see this spring to Journey North!

You can't count on footprints to help, but how can you know you're seeing (and hearing) a loon? It's time to practice, because the loons are coming! Study what they look like, and practice identifying the hoot, the tremolo, the wail and the yodel. Then go out to open lakes to look and listen for these diving birds. Remember to report your sightings to Journey North!

How to Respond to Today's Challenge Questions:

IMPORTANT: 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 ##7 (or #8 or #9).
3. In the body of your message, give your answer to ONE question.

The Next Loon Migration Update Will be Posted on April 5, 2001

Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form

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