Monarch Migration Update: August 30, 2002
Monarch Migration Updates will be posted on FRIDAYS:
Today's Report Includes:
Welcome to Journey South's Migration Season!
The monarch migration takes place without a single sound--all the way to Mexico--but it creates a great stir of excitement in the hearts and voices of people who witness it. Over the next weeks, we'll forward highlights of this fall's migration, as reported from people along the monarchs' path. Please send your own observations and help track the monarch's trip!
Highlights Along the Migration Trail
The migration is off to a slow start compared to what we witnessed last fall. To date, only a few people have been lucky enough to see the massive movements that seemed common in Fall 2001:
"The paucity of monarchs in your area is SO important to document. Keep up the good work," says Dr. Lincoln Brower.
Fewer Monarchs This Fall?
Dr. Karen Oberhauser is conducting an important monarch population study with the help of volunteers across the monarch’s range. Based on data collected this breeding season she notes: “Numbers are much lower than usual in the Northeast, but within the normal range in the upper Midwest. Whether this is due to differences in climatic conditions in these regions (in the upper Midwest we're having more rain than normal and our milkweed looks great, while much of the rest of the country is having a drought), fallout from the Mexico storm and subsequent mortality last winter, or a combination of many factors, we can't know for sure. More years of data will help us to understand cause and effect, but we need many people collecting data in a systematic way.”
The Monarch Tag That Traveled Round Trip
by Elizabeth Howard
Every year at this time, thousands of people tag monarch butterflies and send them, hopefully, on their way to Mexico. Here's a story about one monarch tag that traveled round trip.
Last November, I found a monarch tag at the sanctuaries in Mexico. It had fallen off the butterfly and was lying on the ground, almost hidden in the thick vegetation beneath my feet. I just happened to see it beneath a huge cluster of butterflies deep in the El Rosario sanctuary. Imagine the chance: The tag had ridden all the way to Mexico on the wing of a butterfly and then fallen off!
I carefully tucked the tag into my pocket, but could hardly contain my excitement. Where had the butterfly come from? How far had it flown? Who tagged it?
Traveling home in the bus back to Mexico City, I bounced along for four hours. Winding around corners, and up and down mountain roads, I marveled that the monarch had found the mountain-top sanctuary all on its own.
During the long flight back to Minnesota, traveling for six hours at jet speed, I thought about the tiny butterfly. Perhaps it flew over the same terrain and landmarks I could see below:
The Sierra Madre mountains, the Gulf of Mexico, the U.S. Mexican border, the Mississippi River, Texas, Oklahoma, Kansas, Missouri, Iowa and finally Minnesota. The jet screamed powerfully, burning hundreds of gallons of fuel and guided by humankind’s best technology. The butterfly had traveled slowly and soundlessly, guided by a mysterious and magnificent instinct, and powered by flowers' nectar.
When Monarch Watch checked their records, we found that the butterfly had been tagged the previous August by a man named Tom Murphy. To my great surprise, Tom lived in my own state of Minnesota, just an hour’s drive from my home! As the certificate told, the butterfly had traveled 1,763 miles from Minnesota to Mexico. It had probably flown the same path I watched from the plane’s window.
I was eager to meet the Murphys and kept meaning to contact them. But time passed and I forgot, until one day in early August…
Tagging Monarchs With the Murphys
Tom goes out at dawn so he can capture the monarchs before the sun warms them. Using nets with long poles, he swoops high in the trees where the monarchs cluster.
“The monarchs come in our trees at night, and nectar during the day,” says Tom. "What I call the ‘soft migration’ begins in late July/early August. Monarchs start drifting into our gardens. On a typical night we’ll have 1,000 butterflies roosting in our trees. If there’s a good nectar source the butterflies will stay and ‘tank up.’ If disturbed, I think they head south. But once it gets colder, they don’t linger as long. That is the time I call the ‘hard migration.’
“I've only tagged 550 monarchs to date, compared to 4,000 at the same time last year (August 28th). While this could indicate that the population is down, the numbers tagged could be low this year because the conditions have not been as good for tagging: Nights have not been cool like they were last year. (Tonight's low will be 70F.) Monarchs cluster together tightly on cool nights (say 55F), so big groups of them are easy to capture. Clusters this year are small--say 15-- compared to the groups of 50, 60 or even 100 on a cool night.”
Why do the Murphys have so many monarchs? “If monarchs are around and you have nectar, they’ll come,” says Tom. “When we lived in town, we had only a 10’ garden and the monarchs found it.” The Murphys now have over 2 acres of gardens, planted with flowers high in nectar that bloom during the summer and fall migration.
Challenge Question #1: On Which Side Do Monarchs Cluster?
By watching monarchs closely over the years, Tom has made many interesting observations such as this one: When monarchs are caught in his tent or cold frame, they always gather on the same side. Even if the door behind them is open, they don’t go out!
Challenge Questions: A Central Tool for Student Learning
Journey North provides "Challenge Questions" in each weekly monarch update. Challenge Questions model the thinking/questioning process that scientists use in their work. For more information and suggested classroom use see:
How to Respond to Today's Challenge Question
1. Address an e-mail message
The Next Monarch Migration Update Will Be Posted on September 6, 2002.
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North. All Rights Reserved.