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Monarch
Butterfly Migration Update: February 24, 2006
Today's
Report Includes:
Meet
Dr. Bill Calvert: Our Telephone Tour Guide
Dr. Bill Calvert was one of the first biologists to study the monarchs
at their over-wintering sites in Mexico. For the next three weeks he will
be our special telephone tour guide. But first...
Field
Notes from Mexico from Dr. Bill Calvert This
week's visit was "better than it gets," he said. "A river
of monarchs streaming down from the mountains greeted us. We and our horses
treaded through this sea of butterflies..."
- Why were
the butterflies flying this way? You can read
and hear Dr. Calvert's news and observations.
Food,
Water, Shelter, and Space: A Look at WATER
This season,
we are exploring the monarch's overwintering habitat. How do monarchs
satisfy their need for water? Let's begin with a look at Mexico's wet
and dry seasons. What do you suppose these seasons mean for monarchs?
Mexico's
Wet and Dry Seasons: Dr. Brower’s Precipitation Graph
This
graph is adapted from Dr. Lincoln Brower's research. It shows rainfall in
the sanctuary region for every month of the year. Look carefully at the
graph and describe what you see.
- How have
things changed since the monarchs arrived in November? (Click
graph to enlarge.)
Where
Do Monarchs Get Water? Challenge Question #4
It is now the end of February. The dry season has been underway for four
months as you can see from Dr. Brower's graph. So...
Challenge
Question #4
"Where do you think monarchs get the water they need to survive
the dry season in Mexico? How many sources of water can you imagine?"
(In next week's report you will find ways that are sure to surprise
you!)
- To respond
to this Challenge Question, please follow these instructions.
People
and Water: Life in the Monarch Butterfly Sanctuary Region
"Imagine carrying 800 liters of water every day to your house from
a well a half a mile away…by foot! In the dry season, this is daily
work for me and my family," begins Maria Louise Mondragon. She and
her family own land in the Sierra Chincua Sanctuary and they live in the
valley below.
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Here is their story in both English and Spanish:
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Where
Did They Eat? Discussion of Challenge Question #3
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Good
food as a caterpillar prepares a monarch for survival in Mexico. |
Last week's Challenge Question #3 asked, "If
it’s true that monarchs do not eat while they are in Mexico,
then when and where DID they get the food energy that they are burning
now?"
"Where
they used to live and on their journey," concluded Mrs. Busher's
4th grade class in Wirtz, VA.
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Isn't
that amazing? The nectar a monarch ate last fall as an adult--and
even the milkweed it ate as a caterpillar--can be critical to its
survival in Mexico. Running out of fat is a common cause of death.
"Monarchs that you see littering the ground have usually starved
to death," says Dr. Calvert. |
Do
Monarchs Eat in Winter? A Good Scientist Keeps an Open
Mind!
We hope you noticed the "if" in our question: "If
it’s true that monarchs do not eat...."
"My
caution to you is to not picture anything as 100% true or false,"
wrote Carol Cullar, a Texas naturalist and experienced monarch butterfly
observer. She makes an important point: While it may be true that "a"
monarch "can" go without eating all winter, that does not
mean that "all" monarchs "never" eat!
Is
Nectar Important? More Research and Questions
Scientists have certainly noticed monarchs drinking nectar from flowers
and they have studied the question further. Read carefully and notice how
they continually question their own and others' assumptions, data, methods,
and results. Then try it yourself!
- Dr.
Brower: Monarchs that are visiting flowers
are starving to death. Those butterflies are "running out of gas."
- Dr.
Calvert: "As far as I'm concerned, the
question about whether nectaring is important is unresolved at this
time."
- And
You? Can you see other ways to look at the
question?
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Photos
Courtesy of Dr. Lincoln Brower, Sweet Briar College |
The Next
Monarch Migration Update Will Be Posted on March 3, 2006
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Reserved.
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