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FINAL Loon Migration Update: May
3, 2001
Today's Report Includes:
- LOON-er Landings: This Week's Migration Map and Data
- Dr. Piper Shares Loon Video Clips!
- Egg-cellent Question: Challenge Question #15
- Time for Nesting
- A New Place to Nest: ANPs
- Nice Nurseries Necessary
- Two Similar Species
- Keep Loon Babies Safe
- What's the Rush? Discussion of Challenge Question #12
- Get the Lead Out: Discussion of Challenge Question #13
- Mercury Alert! Discussion of Challenge Question #14
- Year-End Evaluation: Please Share Your Thoughts!
LOON-er Landings
Loons are starting to reach
their finish line! In the past two weeks they have surged north, their wild calls
thrilling more and more observers as they descend upon the opening waters of northern
lakes for a new year. Journey North participants have noticed many loons returning
to lakes still partially ice-covered, so impatient are they and so crowded with ice-out
happening relatively late this spring. But as more and more water opens up, they
can spread out and claim their territorial waters once again. Many loons are settling
into nesting, and that's what this report is about. We start with a peek at real
live loons sliding off their nest!
Dr. Piper Shares Loon Video Clips!
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Dr. Walter Piper studies loons |
(Note: This will open with RealPlayer. After you wait for download, you can enjoy
replaying without the wait.)
Walter took this video on Clear Lake in Oneida Co., Wisconsin on May 30, 1999. Notice
how the loon sitting on the nest slips into the water rather than walking off the
nest. (Loon legs are so far back on their bodies that they have trouble balancing
on their feet.) See if you can follow the action as Walter describes it: "The
clip shows a male incubating, while his mate rests in the water a short distance
away. Soon after the start, the male gets off the nest, followed shortly by a 1-day-old
chick. (Responses of my research interns to the chick can be heard on the audio track.)
The female joins the male and chick. A second egg is still in the nest (perhaps barely
visible in the video)." Walter also told us that this chick and its sibling--still
unhatched --reached adult size and were banded in late summer 1999.
(Note: This will open with RealPlayer. After you wait for download, you can enjoy replaying without the wait.)
Walter took this clip on North Two Lake in June 2000. He says, "This is a
clip of us doing a "playback" to a male to try and induce him to yodel.
Notice that, at the start of the video, you see a loon pair and hear a scratchy-sounding
yodel, which is us playing another male's yodel from a CD player. As the pair and
our canoe drift apart, the male gives a loud and clear yodel in response to our playback,
while the female gives a soft vocalization." Which loon in this pair is the
male, and which the female? (Hint--which loon makes the Yodel call? Which loon--the
female--is smaller?)
Egg-cellent Question!
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Photo Courtesy |
Challenge Question #15:
"Why do loons only have two eggs?"
(To respond to
this question, please follow the instructions below.)
Time for Nesting
Loons are starting to nest on some of their lakes, and will soon be breeding throughout their northern range. You've learned that loons need suitable nest sites. This photo and Dr. Piper's video clip (above in this report) give us an idea of what suitable nest sites look like. A loon pair prefers building their nest where it floats or is at the water's edge by a drop off steep enough so they can arrive and depart under the water. Islands are good locations because the eggs are safe from mammalian predators like raccoons and skunks as well as pet dogs and cats. Being close to the water allows adult loons to slide off the nest when danger approaches and swim back underwater, popping up just at the nest's edge. This is a good way for loons to avoid catching the attention of flying predators like gulls and crows. Whether on the mainland or an island, loons prefer out-of-the-way places that are protected from wind and waves and safe from the commotion of summer canoes an motorboats. The best nest sites also include some overhead cover to hide eggs from the eyes of avian predators, and shelter from wind and waves. If a loon pair loses an egg or chick to predation, they make a replacement nest in a new site. Loons work on building their nests all through incubation, and nests are often used over again.
A New Place to Nest: ANPs
On lakes where loons have lost their natural nest sites, people have helped by placing an artificial nest platform, or ANP. These platforms are floating squares about a square yard (or meter) in size. Platforms are made of cedar logs and buoyant material and covered with ample soil and vegetation for nest-building. ANPs are placed in a typical nest site (a quiet bay or marshy end of the lake) at the beginning of the season and removed after the chicks have left the nest.
Dr. Walter Piper has studied the effect of artificial nesting platforms on the reproductive success of loon pairs. He says, "If anchored offshore in a protected bay, platforms can give loons an appealing site for a nest that is virtually immune from mammalian predation. Our results show clearly that loons find the platforms attractive as nesting sites and that platforms boost reproductive success by about 100 percent. In one case, a new platform even induced loons to breed on a small lake with no previous record of loon breeding. Hence, nesting platforms seem a possible means of mitigating the negative effects of shoreline development and human recreational activity on loon populations."
Nice Nurseries Necessary
Besides their nest site, loon pairs also need a "nursery" pool. Often the nursery pool is a quiet bay, and it can be a fairly long swim away from the nest site. The nursery pool must contain water that's clear enough for the loons to spot their prey. At the same time, the water must be shallow enough limit the size of fish and turtles that prey upon loon babies, reasonably free of scouting eagles and gulls, and bountiful enough to furnish an eleven-week supply of food for the two chicks they will hatch. The best nest territories offer a view of neighboring territories and a pool with little wind and calm water. This helps keep the babies close to the parents and less open to predators.
The chicks spend up to 65 percent of their first week being carried on the back of an adult, but they SWIM from the nest to the nursery when they are less than two days old. When on a parent's back, the chick can clamp its bill onto the adult's feathers to hold on.
At first the chicks eat plant material, crayfish, aquatic invertebrates, and small fishes. As they grow, they eat more and more fish, until finally fish become their major food items. The young can supply much of their own food by the time they are eight weeks old. Adults, including parents with young, leave their territories for more and longer periods as the summer goes on. Chicks leave the nest and are on their own at the age of 75 to 80 days.
As loons build nests, incubate eggs, and raise babies, they fulfill their biological drives and ensure the world a steady supply of loons forever. We wish them well!
Two Similar Species
These two species (loons and people) are alike in some ways. Both prefer the same types of large, clear northern lakes with islands and plenty of fish. For humans, the trip to the lake is a "pleasure migration." For loons, it's a "survival" migration to breed and raise young.
The impact of people on loons takes many forms. Many loon predators, such as raccoons, crows, and gulls, are animals that seem to follow human settlements. That means more of those predators appear where lakeshore is developed for human use. This also means loss of habitat for loons. Disturbance from boats and recreational activities; entanglement of birds in fishing nets and debris in the water; toxic chemicals and oil spills; and even bothering and direct killing are some other dangers. But humans are also helping loons in many ways. Loons use human-created reservoirs for breeding and as migratory stops. Many conservation groups are working to preserve loon habitat and educate people. Read on for more about helping loons.
Keep Loon Babies Safe
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| Photo Courtesy Woody Hagge |
- Lead Poisoning. Sometimes when people are fishing, they lose their sinkers in
the water. These are usually made of lead, which can poison and kill loons. The solution
is to only buy sinkers made from safer metals or plastics.
- Helping Predators Find Baby Loons. Sometimes people in canoes, jet-skis, or boats get too close to a pair of loons and their babies.
Loons make a happy-sounding "tremolo" call that sounds like they're laughing. But when swimming loons make this call, they're definitely NOT happy! The tremolo is actually the call loons make when they are very stressed or scared. If you are in your boat and hear near-by loons making this call, pull back! After the parents have called a few times, if the danger is still present they will sink into the water and swim away. They'll pop up far away and call to their babies to follow them, but meanwhile, eagles and gulls that hear that tremolo call often fly over in hopes of finding an unprotected baby loon. During the time the little loons are scrambling to find their parents again, they can get eaten! To hear the stressed-or-scared tremolo call of the loon, go to:
What's the Rush? Discussion of Challenge Question #12
Last time we asked: "What are some reasons that migrating loons might be in more of a hurry to reach their destination in spring and less of a hurry to get there in fall?"
In spring loons are hormonally primed to reach their breeding lakes. The first to arrive get the best nesting areas. Also, their hormones are driving them to build their nest and produce their eggs. They have to reach the ocean before their lakes freeze, but since they leave as early as August, they have plenty of time to make that journey.
Loons, like many migrants, are fueled in spring by hormones that urge them forward, and also tend to make surges in their territorial feelings, quite possibly making them more uncomfortable in groups. By fall as their hormones quiet, they can mosey on back without the duel urges of setting up territory and breeding to drive them on.
Get the Lead Out: Discussion of Challenge Question #13
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We may have lead around our homes or school buildings without knowing it because we can't see, taste, or smell lead. There may be lead in the dust, paint, or soil in and around our homes, or in our drinking water or food. Someone who works in construction, demolition or painting, with batteries, or in a radiator repair shop or lead factory, or with a hobby that involves lead may unknowingly bring lead into their home on hands or clothes. People may also track in lead from the soil around their homes. Soil very close to homes may be contaminated from lead paint on the outside of the building. Soil by roads or highways may be contaminated from years of exhaust fumes from cars and trucks that used leaded gas. Because lead does not break down naturally, it can remain a problem until it is removed.
Before we knew how harmful it could be to living things, lead was used in paint, gasoline, water pipes, and many other products. Now that we know the dangers of lead, house paint is almost lead-free, leaded gasoline is being phased out, and household plumbing is no longer made with lead materials. But lead sinkers and lead shot are still used in many places by fishers and hunters.
Mercury Alert! Discussion of Challenge Question #14
This Challenge Question asked: "In Little Rock Lake,
- a) approximately how many times more mercury do zooplankton have than phytoplankton?
(About 3.5 times)
b) about how many times more mercury do fish have than zooplankton? (About 4 times)
c) about how many times more mercury do loons have than fish? (About 6 times)
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 #15
3. In the body of your message, give your answer to ONE question.
Year-End Evaluation: Please Share Your Thoughts!
Please take a few minutes to share your suggestions and comments in our Year-End Evaluation Form below. The information you provide at the end of each year is the single most important tool used to guide our planning.
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Journey North |
This is the FINAL Loon Migration Update for year 2001.
We hope you enjoyed learning about this spectacular diver's journey north. Thanks for joining the adventure, and please come back next year!
Copyright 2001 Journey North. All Rights Reserved. Please send all questions, comments, and suggestions to our feedback form
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