Monarch Migration Update: September 13, 2002
Today's Report Includes:
Highlights Along the Migration
Cold Front Triggers Migration
A classic fall cold front spread across the monarch's range this week.
Temperatures dropped, winds shifted from south to north, and observers
everywhere noted its effect:
St. Peter, MN
Jim Gilbert and students tagged 50 monarchs last week at Gustavus Adolphus
College. "Every day, we kept seeing the same ones hanging around
the gardens. A cold front came through yesterday evening and we have
a north wind today. We're not finding a single one with a tag--the old
group is gone and there's a new group of about 25 there today!"
Two Rivers, WI
Along the Lake Michigan shoreline, 320 monarchs were counted during
a 4 minute drive. Some were circling in large groups and others were
heading southwest. "In many areas there were so many monarchs flying
overhead it was difficult to count, particularly while driving!"
As the cold front move southward, Iowa towns reported in like a conductor
announcing stops on a train line: Algona, Altoona, Cedar Rapids, Cresco,
Creston, Malvern, Monona, Pella and Prairie City--each town announced
their news. But along with the excitement came expressions of sadness
in memory of last September 11:
A cold front was passing through the state, and by late afternoon, migrating
monarchs were riding and floating on the wind on their southerly journey.
In 45 minutes--from 5:15 p.m. to 6 p.m.--150 monarchs were counted high
in the sky flying over our butterfly garden. Some could be seen with
the naked eye, but this was a day when binoculars were needed to experience
the magnitude of the event.
Cedar Rapids, IA
At 5 pm, a steady flow of monarchs is now occurring. They are flying
singly, rather high and almost out of view, at a rate of 6 per minute.
The weather took a marked turn today, only 69 compared to high 80's
yesterday. The winds are 17 mph, NNW and it is very grey. If it was
colder, I'd call it blustery.
This evening, at about 6 pm I looked up and saw many Monarchs flying
by, I counted about 60 but sure there were a lot more. We've had hot
weather, but a cold front is coming through now.
The migration has started to pass through our playground at school.
Today, at 10:00 AM, we spotted 10 Monarchs heading south like they were
on a mission. This is definitely a bright spot on this solemn day.
Fifth and 6th graders at Crestwood Elementary released monarchs today
as a part of our special Sept. 11 ceremony--true symbols of freedom
Fall Monarch Migration: About
Cold Fronts and Winds
"It's easy to see why monarchs
come in on cold fronts. It's like catching a bus going your way - in this
case the ride is even free!" says Dr. Calvert. For more information
about monarch migration and weather see:
News Spotty from South and
From his vantage point in near the Gulf Coast, lepidopterist Gary Ross
summarizes the situation to the south:
Baton Rouge, LA
are now well represented in the lower Midwest as well as the Gulf South.
Also, many females are ovipositing (laying eggs)."
Meanwhile, the only news from the northeast, where the population appears
to be extremely low, were scattered sightings of single monarchs:
Today I saw a lone monarch. This is the fourth one I have seen this
This is only the 2nd monarch I have seen all summer.
Just looking out the window at the leaves blowing and there's the very
first monarch I've seen this September.
Also Seen Migrating This
A massive dragonfly migration occurred on Monday evening as the cold front
moved through Minnesota. Dragonflies filled the skies like hundreds of miniature
helicopters escorting the monarchs that were traveling with them. People
living 10 miles apart witnessed the event, meaning this wave of migration
was at LEAST that many miles wide. "Massive swarms commonly follow
the passage of cold fronts" says the North
American Dragonfly Migration Project website. Where are the dragonflies
going? And who eats THEM along the way? A parade crosses the sky every year
at this time, with predator following prey. See:
What’s Up? Lie Down
and You’ll See
Dr. Calvert watches monarchs
arriving at the sanctuaries in Mexico.
With eyes on the fronts of our faces, we rarely look upward. So lie down
for awhile this fall, look up at the sky, and see what you see while watching
for monarchs. In this photo, monarch biologist Dr. Bill Calvert demonstrates
sky-watching position. (Being a biologist is a tough job!)
- Please tell us what other creatures are migrating where you live.
(Report as "Fall Nature Notes.")
Analyzing Data From
Mr. Viger’s Monarch Roost
During fall migration, some lucky people have thousands of monarchs pause
in their yards at overnight roosts. Mr. Viger of Campbell, MN is one such
person. He sent these pictures to share. How many tagged butterflies can
you find in this roost?
of my two kids (Alex age 5 and Emily age 3) from last year has an interesting
story," said Mr. Viger. "We tagged a few butterflies in the
morning and I told the kids to bring their last ones to the house and
I would get a picture. One of those butterflies was recovered in Mexico.
It's neat to have a picture of a butterfly (I'm not sure which one)
that made it to Mexico.
"It does seem
like the migration is a little later this year," he continued.
"So far, 38% of this year's butterflies have come after the last
date they were here last year (9/6/01). Of course, the most obvious
difference from last year is the lower number of butterflies. So far
this year, 740 have visited compared to 10,400 last year (just 7.1%)."
Each day Mr. Viger counts the monarchs, tags them, and records information
about the wind and weather. Last year monarchs were present for almost
3 weeks and he noticed an interesting pattern. You can see it too if you
look carefully at his data between August 27 and September 6.
(To respond to this question, please follow the instructions
Try This! Estimating the Number of Monarchs
in a Roost
People are dazzled by the beauty of fall "butterfly trees." How
can you estimate the number roosting? Scientists often use still photos
to help estimate numbers, whether counting whales or caribou, bats or butterflies.
Here's a chance to practice. As a class, take a 10-second look at Picture
#1 and record the number of butterflies you think you just saw.
of Tim Mostrom
Discussion of Challenge Question #2
Last week we read about scientists who changed monarchs' biological clocks
to study how they navigate. To help understand how our behavior is effected
by our sense of time, we asked you to imagine what would happen if YOUR
biological clock were changed by 6 hours.
students in Texas wrote, "Our third grade GT class thinks that
if we arrived at school 6 hours early nothing would be going on. The
school would be deserted. We would not be able to get in. If we arrived
6 hours late we would get to school at 2:00 P.M. It would almost be
time to go home. We might get in trouble. We would be counted absent."
Similarly, when the monarchs' clocks were off, they behaved as their
internal clocks instructed. They flew in the wrong direction because the
outside environment--the location of the sun--was not where it should
have been to guide them properly. (See last week's story.)
Symbolic Migration: Send Your Smiling
Only 29 more butterfly-making
days before the October 11th postmark deadline.
Tip: Mexican students are eager to meet you! If you can, glue your photo
to your monarch and send your smiling face to Mexico to greet your new
friend. In past years, we've seen wonderful butterflies with photos for
faces fly by. (See example on the web.)
Please Report Your Sightings!
We can't track migration without your help. Please come to the web and share
How to Respond to
Today's Challenge Question
1. Address an e-mail message to:
2. In the Subject Line write: Challenge Question #3
3. In the body of the message, answer the question above.
The Next Monarch Migration Update Will Be Posted on September
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