Monarch
Butterfly Migration Update: September 12, 2003
Today’s
Update Includes:
Highlights
from the Migration Trail
It was peak migration in Iowa last week, and the monarchs have now clearly
moved into Nebraska, Illinois, Indiana, Ohio and even Missouri and Kansas.
- Mrs. Rose
of St. Joseph School found her first roost of the year in Lincoln, NE.
- A boy
in Marshall, IN was climbing a tree when he discovered monarchs flying
in to settle for the night.
- Dr. Chip
Taylor of Monarch
Watch says the leading edge of the migration just hit eastern Kansas
on September 6, a little early.
The map on
the right shows drought conditions in the U.S. Find the regions with moderate,
severe and extreme drought. How might drought affect the monarchs? List
all the ways you can imagine.
"Central
Iowa is exceedingly dry now," says Robert Woodward of Drake University.
"Some wildflowers are drying out early and dying. Does the dry
weather affect the monarch migration--the timing of it and the places
visited?" he wonders.
- The lack
of sightings reported from Wisconsin is interesting. An observer on
the west shore of Lake Michigan has seen little movement, not "the
normal 10-25 per minute when the migration starts."
- Further
to the east in Ontario, Don Davis reported a large westerly movement
of monarchs along the north shore of Lake Ontario, from at least Oshawa
to Oakville on Sunday, Sept. 8. Perhaps these were among the monarchs
counted the next day to the west, at Ontario’s Holiday Beach Migration
Observatory near Detroit, MI. Monday was a big migration day there,
with 1,380 monarchs counted compared to only 50 any previous day.
- The first
big surge was reported along the East Coast on September 6 from Long
Island: "There were thousands of monarchs migrating along Jones
Beach. I counted 40 in one minute."
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Since August,
it seems an unusually high number of early monarch sightings have been
reported from Texas and other southern states. Questions surround early
sightings at these latitudes, so it's hard to know whether to include
any on the migration map. For the record, the map on the right shows all
reports received to date.
Monarch
Off the Map: Discussion of Challenge Question #2
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The
Prince of Wales visiting the monarch sanctuaries in Mexico |
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Dr.
Bill Calvert |
After last week’s
report of a monarch across the Atlantic we asked, "Where do you think
the monarch that was sighted in Cornwall, England came from? Describe how
you think it got there." "The
sightings in this country are mainly attributed to North American migrants
that have blown over here, and a few escapees from butterfly farms,"
said Vince Smith, who reported the monarch. "This article sums up
the general consensus of opinion of how they arrive in the UK."
"It's
conceivable that they were carried aloft and blown over 2,000 miles,"
believes monarch biologist Dr. Bill Calvert. "It would take more
than a day, and monarchs don't normally fly at night--they get disoriented
and can't fly. But if caught in high velocity, high altitude winds they
can't come down."
So nobody
knows for sure! Students debated the question and came up with hypotheses
similar to the scientists'. Mrs. Koch's Class in Barnesville, Ohio had
the winning number, including their “accidental tourist” hypothesis.
The
Monarchs That Flew the Wrong Way: Two True Stories
Here are two
true stories about tagged monarchs that were found in unexpected places.
What can we learn about migration from monarchs that didn’t make it
to Mexico?
Free
Ride to Mexico: Glide Don't Flap
Why do monarchs
ride with the wind, and risk being blown off course? When monarchs glide
they burn no more energy than when sitting still (called their "resting
metabolism"). Gliding provides a free ride, like riding a bike downhill.
In contrast, "flapping" or "powered" flight takes much
more energy. According to calculations by Dr. David Gibo, who’s a
glider pilot himself, a monarch burns 140 mg of fat to either:
- fly for
more than 1,000 hours in soaring/gliding flight OR
- fly for
44 hours in flapping flight
How
Expensive is Flapping Flight?
Challenge
Question #4:
"According to the example from Dr. Gibo, how many times more energy
is burned during flapping flight than during soaring/gliding flight?"
(To
respond to this question, please follow the instructions below.)
Wind
and Thermals: Two Ways Butterflies Fly Free
On windy
days monarchs can catch a free ride with the wind, and glide effortlessly
southward.
A
thermal is a column of rising air, caused by uneven heating of the
earth. |
On sunny
days, monarchs can be lifted by thermals. They spiral higher and higher
in tight circles, then glide downward and southward to catch the next
thermal.
Field
Trip in the Sky: Flying in a Thermal
By Elizabeth Howard
I've read
a lot about thermals, but now I understand them. Thanks to Dr. Ian Worley,
pilot and professor at the University of Vermont, I went up in the sky
myself this week and found out what it's like to fly in a thermal.
"I
take my students on aerial field trips because we can see things from
the sky that we can't see so well from the ground," said Dr. Worley.
"But more excitingly, we can have a feel of the sky and learn its
shape--what’s going on in the air-- because though the air is
sometimes invisible we can feel it with the airplane. Today, we’re
off looking for thermals, those rising columns of air that take gliders
and hawks and butterflies to higher heights so they can glide to the
next thermal and find their way south during migration."
We hopped
aboard his plane and headed for the sky. But where would we find a thermal?
And, I wondered nervously, what WOULD it feel like to fly a small plane
through one?
Dr. Worley
spotted a fluffy cumulous cloud and banked the plane to the left. A cumulous
cloud is the tell-tale sign of a thermal. The cloud forms when the column
of air rises, and then cools at higher altitudes. The moisture in the
air condenses and forms the cloud.
"We're
going to fly to it and see if we can get an upward rise of air, which
we'll feel as a bump. And if it's a REALLY good bump we'll feel it in
the seat of our pants," he said.
So off we
flew toward the cloud. Here are photos, video and a transcript of the
trip so you can find out what happened:
- Field
Trip in the Sky: Flying in a Thermal
Challenge Question #5:
"When we hit the thermal, the plane rose at a rate of 500 feet/minute
for 30 seconds. How many feet upward did the thermal carry the plane?
How did the plane's speed compare to the speed of a typical elevator?"
(To
respond to this question, please follow the instructions below.)
Migration
Rate Math: Discussion of Challenge Question #3
Last week we challenged you to compare migration reports from different
observers by converting their observations to the same units, "monarchs
per hour." Who saw the most monarchs? Mr. Falgout's fifth grade class
at Glenwood School in North Carolina arranged the observations in order
from most to fewest. Here's the order (plus the number of monarchs per hour
each observer saw):
- Observer
#5: (1,032 monarchs/hour)
- Observer
#4: (82 monarchs/hour)
- Observer
#2: (32 monarchs/hour)
- Observer
#1: (24 monarchs/hour)
- Observer
#3: (8 monarchs/hour)
How
to Respond to Today's Challenge Question
1. Address an e-mail message to: jn-challenge-monarch@learner.org
2. In the Subject Line of the message write: Challenge Question #4 (or #5)
3. In the body of the message, answer the question above.
The Next Monarch Migration Update Will Be Posted on September
19, 2003.
Copyright 2003 Journey
North. All Rights Reserved.
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