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Monarch Butterfly Migration Update: April 14, 2006
 This Week's Migration Map and Data

Use today's data to make your own map, or print and analyze our map:

News from the Migration Trail

Thanks to everyone for contributing! There are 55 new sightings on this week's map.

The migration's leading edge has now advanced to 39N, far beyond its position at 36N just one week ago.

  • How many miles is that?
  • How many miles per day did the migration advance, on average? (Assume 69 miles for every degree latitude.)
  • If they continue at this rate, predict when the first monarchs will reach you.
Time to Revisit Views About Monarch Migration? Scientists Comment

This is an unusual year! Monarchs overwintered as far north as Virginia and began appearing inland in early spring. Is this significant? Biologists Andy Davis and Dr. Sonia Altizer of the University of Georgia shared their thoughts:

"We are not aware of previous studies documenting this high number of sightings, and these reports may stimulate scientists to revisit common views of monarch migration and overwintering behavior," they began.

Scientists Catching Monarchs
Andy Davis and Sonia Altizer
Do Only Females Migrate? Please Contribute Your Observations

Andy Davis made an interesting observation this spring. Of the six monarchs he caught migrating from Mexico, all were females!

"That got us wondering," he said, "where are the males in the spring? Could this have just been a fluke, or do males really make the spring migration at all?"

The Life Cycle Continues...
Ms. Monarch’s Final Days and Her First Chrysalis

"Well the day finally arrived..." Dr. Edson wrote sadly at noon yesterday. After laying a grand total of 758 eggs, Ms. Monarch's life finally came to an end.

Special thanks to Jim Edson for sharing Ms. Monarch's story with us! He faithfully counted her eggs every day at noon for over a month, and gave us new insights about the monarch life cycle. Thank you, Jim!

But the story is not over, he reminds us: "Now we wait for the first butterfly," he said on Sunday, the day Ms. Monarch's first child became a chrysalis. Soon her children will continue the journey north. Get ready to watch for fresh-winged butterflies!


Thank you
Dr. Edson!

 
Over 750 Eggs! What Happens to Them All?

Survival is not easy. "Only about 10% of monarch eggs make it to the 5th instar," concludes Dr. Karen Oberhauser, based on data collected by her volunteer network, the "Monarch Larva Monitoring Project."

This means 90% die before they even become a chrysalis! Exactly what do monarchs need to survive? What threats do they face? Begin with an egg and keep a list. We've started with three needs, all drawn from today’s update (Read on...)

Monarch Larva Monitoring Project: You Can Help With Research!

Volunteers are invited to participate in Dr. Oberhauser's research this spring and summer. Her project is gathering important information about monarch biology.

First a Monarch Eats its Shell and Then...Discussion of Challenge Question #10

Last week Dr. Brower said, "Monarchs have to be careful not to lay more than one egg per plant (or leaf) because, when they hatch, the caterpillar will eat its own eggshell. The next thing it will do is wander over and___."

"Eat the milkweed plant," said Amanda S. She is so right! Monarchs eat a tremendous amount of milkweed. In fact, a monarch increases in mass by 2,000 times while it's a caterpillar. This amazing change takes place in only about 9-14 days. Imagine gaining weight the way monarch larvae do!

Challenge Question #11
"How much would you weigh if your weight increased 2,000 times? With your answer, name something that weighs the same amount."

Eating its shell
Monarch_Summer2002_049
Do you see two monarchs?
One is 2,000 times larger!
Speaking of Eggs: A Conversation With Dr. Lincoln Brower

There is another reason female monarchs usually lay one egg per leaf or plant. Listen to Dr. Brower. You are sure to be surprised. He watched monarch eggs closely and here is what he discovered:

For Mexican Students: Noticia de la migracion de la mariposa monarca

As the butterflies fly over your homes, schools and cities, we're sending the news back to the students in Mexico so they can track the migration too. Here is this month's report in Spanish, with an English translation:

Symbolic Butterflies to Fly on Earth Day (April 22, 2006)
Over 50,000 Symbolic Butterflies will begin the final leg of their journey home this Saturday, Earth Day. How fitting that mailboxes across North America will be filled with these symbols of conservation and international cooperation. We have a new map this year that will work like an online lost and found, so you may find where your own butterflies landed! Stay tuned...
Wanted: Your Monarch and Milkweed Sightings

We can't track migration without your help!

The Next Monarch Migration Update Will Be Posted on April 21, 2006


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