Butterfly Migration Update: October 17, 2003
From the Migration Trail
continued in full force across Texas during the last week. Like a postponed
parade, its progress southward had been held up by the rainy weekend. But
when the weather cleared, “We began seeing monarchs dropping down
out of the clouds,” said one awestruck observer. The migration also
poured across the border into Mexico in the wake of the cold front. U.S.
weather maps may stop at the border, but weather systems and monarchs move
across without notice--and bring the same excitement to the people waiting
Map to Read Highlights Along the Migration Trail
fin llegaron!," wrote Rocio Trevino. "Después de varios
días de llamadas y correos electrónicos preguntando por
qué no llegaban las mariposas, al fin las tenemos con nosotros,
volando a diferentes alturas, tranquilas como sin prisa por llegar a
su destino, disfrutando de los campos floridos que nos han dejado las
lluvias de los últimos días."
are other highlights of the week:
first grade class at Willie Brown Elementary in Mansfield, TX saw the
most monarchs they had ever seenor even imagined:
we walked out of the gym at 11:10 on Friday, we looked up to see a dark
gray cloud. No, it wasn't a rain cloud; we were watching thousands of
monarchs flying south. The class observed for thirty minutes as the
mass of monarchs grew smaller and smaller. We found that, if we were
very quiet, some of the butterflies would float down close enough for
us to be able to see through their wings. What a sight!"
are here! Finally!" called out Carol Cullar from Eagle Pass, TX.
"I had to leave the house at 5 and didn't see a single monarch
all afternoon, but I took the flashlight out just now and found one
tree with several branches covered. NOW THEY'RE HERE!!!!!!!!"
days of near constant drizzling rain, I did not expect to see so many
butterflies in our trees. But, this afternoon the rain stopped and I
see they have come to roost in huge numbers. Two days ago, I estimated
their numbers to be a few hundred; today I am seeing several thousand.
I wish I knew a better way of determining their numbers. Anyone know
the Number of Monarchs in a Roost
Scientists often use still photos to help estimate numbers, whether counting
whales or caribou, bats or butterflies. Here's a chance to practice so you're
ready if you happen upon a major monarch roost some day:
Migration Pathways in Texas
the Texas Gulf Coast, Harlen Aschen reported: "The fall migration of
monarchs has started along the Texas midcoast. Between 5:45 and 6:15 we
were counting almost one a minute dropping out of the sky near the north
end of the Lavaca Bay Causeway."
migration actually moves through Texas on two different flyways, and at
two different times, or pulses. The first pulse travels down the Central
Flyway and the second pulse moves along what's known as the Gulf Coast
Flyway. The monarchs that use the Central Flyway probably come from the
mid-western prairie states. The coastal monarchs most likely come from
east of the Mississippi River. Typically, the second pulse reaches Texas
later because the monarchs have come from farther away. Look at a map
of North America and compare it to this map of migration pathways in Texas,
made with Texas Monarch Watch data.
and Waiting at the Mexican Sanctuaries
Once again, no monarchs were seen last week by students who are waiting
beside the sanctuaries in Mexico:
Importance of Negative Data: Challenge Question
For 4 weeks in a row, these students have been watching for the migration
to arrive. Day after day, they report having seen "zero" monarchs.
Watching for something, and recording what you DON’T see, is called
collecting "negative data."
"What wouldn’t we know about the arrival of the migration
in Mexico without having collected 'negative' data? When the monarchs
finally do arrive, explain why the zeros will be so helpful."
respond to this question, please follow the instructions below.)
a Late-Season Monarch Make it to Mexico?
fact that it's mid-October, monarchs are still migrating down from the north.
They were even reported last week in places like Ontario, Minnesota, Michigan,
Vermont and New York.
Tagged by Mrs. Kloewer's Class
in York, Nebraska
fall weather suddenly turns cold, many students write to say they’re
worried about the butterflies they're raising in their classrooms. Is
it possible for a late-season monarch to make it to Mexico? You can answer
this question yourself by analyzing tagging data. Tag recoveries are posted
on the Monarch Watch site. (A "recovery" means the tagged butterfly
was captured again later.) Look through the records and find recoveries
of monarchs that were tagged in your state or province. What is the latest
date a tagged monarch has made it to Mexico?
Adaptations: Migration as a Survival Strategy
An "adaptation" is a physical or behavioral feature that evolved
in response to an organism's environment, due to pressures for survival.
How a species looks (its anatomy and morphology), as well as how it behaves
(how it moves, obtains food, reproduces, responds to danger, etc.) are all
adaptations for survival.
and Milkweed: Comparing Strategies
Monarchs and milkweed occupy the same habitat during the breeding season.
But when freezing temperatures approach, they show very different adaptations
for survival. Monarch butterflies carry their seed stock all the way to
Mexico; Milkweed seeds stay home. When the two meet again next spring, imagine
how different their lives will have been!
the life cycles of monarchs and milkweed. Draw a picture of each during
- How are
milkweed and monarch survival strategies similar in the fall? How are
seeds blowing in the wind
butterflies flying to Mexico
Lincoln Brower, Sweet Briar College
Cheers for the Ones That Spend the Winter!
As incredible as monarch migration is, other butterflies and moths are
incredible in the fact that they do NOT migrate! This winter, when you're
freeeeeeeezing cold, think about the moths and butterflies that stick
around for the winter. How do they do it? Learn about these three species
and let us know:
Do These Survive the Cold?
"In what stage of their life cycle do these butterflies and moths
respond to this question, please follow the instructions below.)
to Respond to Today's Challenge Question
1. Address an e-mail message to: email@example.com
2. In the Subject Line of the message write: Challenge Question #11 (or
3. In the body of the message, answer the question above.
Next Monarch Migration Update Will Be Posted on October 24, 2003.
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