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Loon Migration Update: April 20, 2000

Today's Report Includes:

Back on Territory
Molted into their beautiful breeding plumage and filling the north with their haunting calls, loons dropped down into clear northern lakes as fast as the ice went out. (See the latest migration map and data.

In our next update, we'll focus in on one state, Wisconsin, so you can analyze just how quickly the loon migration actually takes place.Why the hurry?

It's important that loons arrive as early as possible to claim a good territory and to protect and defend it. When people say "My loons are back again this year," they're probably right! Loons may live for 25 or 30 years, and growing evidence suggests they return to the same territories every year. Banded adults have been recaptured on the same territory in years following the banding. Now scientists use sonograms (printouts of vocalizations) to check whether or not the same loons occupy the same territories from year to year.

In "The Common Loon: Spirit of Northern Lakes," author Judith McIntyre says: "Yodels are distinctive, and throughout the summer they sound the same for each loon. Sonogram analysis confirms that during the summer, each individual male loon gives the same yodel, distinctive from those of other male loons in the population."

Common LoonTerritories must provide all the needs of loons during summer: a place to nest, raise young, and find food. Territories come in many sizes. McIntyre says: "The smallest are five-to six-hectare lakes. Adults defending these tiny ponds use adjacent bodies of water for their own feeding, but food for their young comes only from the territorial lake. Lakes smaller than 80 hectares generally support only one pair of loons, but the shape of the lake also influences the number of pairs it can support." A small lake may support two pairs if bays or islands form visual barriers. The larger the lakes, the larger the territories seem to be. Territory size changes (shrinks or expands) during the breeding season. Evidence shows that loons nest and raise young on both deep and shallow lakes.

The territory may be home sweet home, but loons get around. Young can supply much of their own food by the time they are eight weeks old, and adults including parents, leave their territories more often and for longer times as the summer goes on. According to Judith McIntyre, if their territories are on small lakes, adults go to other lakes. If their territories are on large lakes with many loon pairs, they swim to neutral places on their lake. Adults leave their territories in early morning and toward evening for social gatherings.

By our next Update, it will be time to talk about nesting and nurseries!

Challenge Question #15:
"Some loons don't arrive until after territories have been established and nesting has begun. What might be some reasons?"

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

The Loon Ranger Reports
Common LoonOne of this week's sightings came from Jim Anderson in Michigan: "Let it be known that the loons have landed on the pond in Montcalm County on the 16th day April 2000, just a little west of Indian Lakes." (43.42N,-85.50W) (5anders@pathwaynet.com)

That's a sighting Jim Anderson has been itching to report! These loons and their territory are well known to Jim, who calls himself The Loon Ranger. Most of us aren't lucky enough to see loons or their chicks up close, let alone see an egg hatch. But Jim was! He shares the story behind his canoe quests for loon photographs. See The Loon Ranger's story at:

Earth Day Message
April 22 is Earth Day, but people need to make every day Earth Day. It certainly would help the loons! Common loons are still plentiful in most of Alaska and Canada, but their numbers and range have decreased in the lower 48 United States. The estimated 20,000 loons in the Upper Great Lakes States of Minnesota, Wisconsin, and Michigan comprise nearly three-quarters of the loon population outside of Alaska. Research suggests that loons in Michigan and Wisconsin have rebounded from drastic declines earlier in the 1900s, and the loon population in Minnesota is still thriving. But many threats remain.

Human activities are the biggest reason for loons vanishing from many lakes. Development of shorelines and islands for summer homes, campgrounds, and marinas has destroyed traditional nesting areas and other suitable sites. Disturbance of loons, especially during sensitive nesting and chick-rearing periods, can reduce or wipe out loon populations. Pollution of lakes used by nesting loons can lead to buildup of toxins in eggs and young, and the loss of food for chicks and adults.

What kinds of toxins are we talking about? Lead and mercury are two. Where do these toxins come from, and how do they get into loons? Read on for ways to help safeguard loons and other wildlife from toxins so you can make EVERY day Earth Day!

Going Fishing? Get the Lead Out!
Common LoonWhen lead fishing sinkers are lost through broken fishlines or other means, birds such as loons, swans, and eagles can accidentally eat them. Lead is a toxic metal that harms the nervous and reproductive systems of mammals and birds. Lead is found in most fishing sinkers and some shot, and it's poisoning loons and other wildlife. In areas where loons breed, the Great Lakes region, northeastern United States, and eastern Canada, lead poisoning from fishing sinkers or jigs may account for up to 50 percent of the dead adult loons found by researchers. Lead poisoning does not have to happen. Sinkers and jigs do not have to be made of lead. You can help save loons from lead poisoning deaths with a few easy measures. See our lesson on lead poisoning, with an address for FREE steel sinkers to use yourself or to give to someone who fishes:

Mercury Alert!
Lead isn't the only heavy metal threat to loons, wildlife, and water supplies. See Journey North's lesson on mercury and its connection to the loon's food chain at:

Then use the information in the lesson to answer:

Challenge Question #16:
"In Little Rock Lake, approximately how many times more mercury do zooplankton have than phytoplankton? About how many times more mercury do fish have than zooplankton? About how many times more mercury do loons have than fish? (For extra credit, make a diagram or chart showing the mercury amounts found at each level of the food pyramid.)"

Challenge Question #17:
"What factors do you think would contribute to the mercury amounts found at each level of the food chain?"

Challenge Question #18:
"In one Ontario study area the yellow perch were found to have 360 ppb of mercury. How many times more mercury was found in these fish than in the fish in Little Rock Lake?"

Challenge Question #19:
"What kinds of things in our environment contain lead?"

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

Got a Question? Ask the Expert!
Mark your calendar for May 12 when Ted Gostomski's answers to your loon questions will be on the web. Don't forget to send him your questions! Deadline is April 28.

Nesting, or Just Passing Through? Discussion of Challenge Question #13
"What clues can you look for to tell whether loons are just passing through, or might be staying to nest?"

Rebecca and Cameron Zacher sent a great answer: "If the loons are going to stay and build a nest they will fight off other loons who land there. When they are just traveling there can be lots of loons on a lake together." (zack@alaska.net)

It helps if you know whether the lakes farther north are free of ice yet. If they aren't, then large groups of loons often end up staying on an ice-free lake until ice-out occurs on their breeding lakes. If those loons aren't fighting to defend territory, it's likely they're just passing through. But if several loons are on a lake but spaced apart (like opposite ends of the lake, or in different coves) and not interacting with others, they're likely on territory. Head bobbing and other courting behaviors are signs they're on territory. Hearing the male hoot call at night is another clue; the hoot is a territorial defense call. Finally, if you actually see a loon sitting on a nest, you have absolute proof that the loons are on territory!
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 #15 (or #16 or #17 or #18 or #19).
3. In the body of your message, give your answer to ONE question.

The Next Loon Migration Update Will be Posted on May 4, 2000

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