Fall's Journey South: October 20, 2000
Today's Report Includes:
Dressing for a First Journey
By their fourth week, the chicks' first real flying feathers started to erupt. The wing feathers started popping through their skin around the time they were 24 days old. The tail feathers started around day 27. These first flight feathers had to be strong. These are the feathers that carry young chicks all the way to the ocean! It takes a long time for these important feathers to reach full size. Fifty-one days after first erupting through the skin, the primary wing feathers are only 80% of their full size. Even so, they're long enough for the young birds to make their first flights.
Loon body feathers have to be dense enough so water can't seep through them and thick enough to hold the loon's body warmth. So baby loons have to grow over 10,000 feathers, which takes a lot of energy! By January, even though the chicks' bodies have stopped growing, both this year's baby loons and all the adult loons will already be growing a whole new set of feathers. This happens even though the feathers they're growing now will be only a few months old! You may wonder: Is growing so many new feathers a waste of energy? Why do loons grow new body feathers twice a year?
During the time the loon wears a feather, the tip wears off and the feather may bend or break. Feathers also fade in light. Since loons spend their entire lives either flying in the sky, swimming in open water, or sitting at the water's edge, they hardly ever get to hide in the shade. Loons spend almost 100% of their daylight hours in strong sunlight. How does this affect their feathers? The following experiment will give you an idea:
1. Cut a bright piece of construction paper into three equal strips.
2. Put one strip in a dark drawer or desk. Tape the other two to the indoor side of a sunny window.
3. Take one strip down after a day and compare it to the strip in the dark drawer.
4. Take the other strip down after a week and compare it to the one in the dark drawer. What happened? (Read on to find out why.)
Pigments that give feathers their color also give them some of their strength. When pigments break down in light, the feathers fade, like your paper strips in the experiment above. The feathers also become weaker. One by one, the thousands of fragile little barbs that hold each feather together break down. Once broken, the barbs can't be fixed. That's why loons need to get new body feathers twice a year. But the flying feathers are different. They're so strong that they last a whole year.
Once loons are properly feathered, their bodies still need to gain extra fat. They will burn up this fat to get the energy needed for the hard work of flying.
Preparing for Takeoff! Challenge Question #7
In autumn, there are three groups of loons: this year's babies, their parents, and the adult loons that didn't raise babies. Think about how they must prepare for the long journey south, and answer this week's Challenge Question:
East or West? Answer to Challenge Question #5
Last time we asked: "East or West? Which species--Baltimore or Bullock's--is found in the West, and which species is found in the East?"
Maryland second graders Ben and Katherine had the answer plus a little extra news. They wrote: "Bullock's are found in the West. Baltimore Orioles live in the East. We live in the East. We live in Maryland, close to Baltimore but we only saw two Baltimore Orioles this spring eating oranges we left hanging from our tree." (firstname.lastname@example.org)
Good answer, and good oriole watching!
Molting Matters! Response to Challenge Question #6
The question was: "Which oriole (Baltimore or Bullock's) do you think molts on its summer breeding grounds? Which oriole probably molts on its winter feeding grounds?"
Journey North's bird expert Laura Erickson explained the answer. Baltimore Orioles molt on their summer breeding grounds. This makes sense because these birds live in areas that normally have plenty of moisture to produce abundant insects and fruits. Baltimore Orioles have enough resources on their breeding grounds to raise their babies and molt before migrating south. But Bullock's Orioles breed in drier places, where food isn't as varied and abundant. These birds wait until they reach the plentiful food sources on their wintering grounds before they grow a new set of feathers.
How to Respond to Today's Challenge Question:
1. Address an e-mail message to: email@example.com
2. In the Subject Line of your message write: Challenge Question #7.
3. In the body of the message, answer the Challenge Question.
The Next Journey South Update Will Be Posted on November 3, 2000.
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