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Monarch Butterfly Migration Update: September 5, 2003

Today’s Update Includes:

Highlights From the Migration Trail

Click Map to Read Highlights Along the Migration Trail

The strongest migration of the season to date was reported last week across Minnesota. Neighbors in Iowa are now noticing the influx as monarchs move southward. Monarchs were also on the move in Michigan, Wisconsin, Illinois, Missouri and other Midwest states. Migrating monarchs were even on the runway at the Detroit airport, beside jumbo jets heading for their own international destinations. In the Northeast, butterflies were flying south across the St. Lawrence River in New York, alongside raptors in Ontario, and touched down at Butler Elementary's butterfly garden in Mystic, Connecticut. For several weeks, scattered sightings have also been reported all the way to Texas.

Tracking the fall migration is tricky. It's impossible to know the FIRST migrating monarch when we see it, as we can in the spring. Thus, the sightings selected for the migration map are simply "migration highlights." Some are roost sites, some signify peak migration, and others are noteworthy observations made during the monarch's remarkable journey.

Monarch Off the Map: How Can a Monarch Land in England?
The Prince of Wales visiting the monarch sanctuaries in Mexico
A surprising report arrived on Monday from across the ocean! A monarch was spotted in Penzance, England (50.15 N, 5.50 W), near the tip of the Land's End peninsula in Cornwall. Milkweed doesn't grow in the United Kingdom so it couldn't have been a local monarch. The nearest breeding populations of monarchs are found in southern Spain and North Africa, but those are non-migratory populations.

So where did the monarch come from? Scientists there have considered 4 main hypotheses. Next week we'll provide an article that summarizes them. Meanwhile, pull out a map and consider the question yourself:

Challenge Question #2
"Where do you think the monarch that was sighted in Cornwall, England came from? Describe how you think it got there."

(To respond to this question, please follow the instructions below.)

Don't Compare Apples and Oranges:
Calculate the Migration Rate

As you monitor the migration this fall, quantify your sightings the way good scientists do. Tell us how many monarchs you see AND how long you were watching. Then calculate the migration rate. (For standard units, use monarchs per minute and/or monarch per hour). By calculating the migrate rate, you can compare one observation to the next.

Who Saw The Most Monarchs? Challenge Question #3
Here are some examples that people reported this week. Who saw the most monarchs?
  • Observer #1) I'm reporting the first sighting of several butterflies from my 22nd floor residence on Chicago's north side on the lakefront. I witnessed around two dozen an hour.
  • Observer #2) During my 5:30 p.m. to 5:45 p.m. observation time, I saw eight Monarch Butterflies flying overhead.
  • Observer #3) The students reported seeing two Monarch Butterflies on the playground between 2:00 p.m. and 2:15 p.m. today.
  • Observer #4) During a three-hour morning visit to Neal Smith National Wildlife refuge in Iowa, 246 monarchs were observed.
  • Observer #5) I counted 86 monarchs in 5 minutes.

    Challenge Question #3:
    "Who saw the most monarchs? Arrange the observations in order, from the observer who saw the most to the fewest monarchs. In your answer, use standard units to compare the number of monarchs (monarchs/hour or monarchs/minute)."

(To respond to this question, please follow the instructions below.)

Migration Viewing Tip: Binoculars Needed During Strong North Wind
By Elizabeth Howard

I saw an impressive migration last Friday in Minnesota, but I almost missed it entirely. The wind was blowing from the north and I wasn't seeing many monarchs. Then I remembered Bill Calvert's tip for watching monarch migration during a north wind:

"Use binoculars and look beneath the clouds. The butterflies travel way up high and are easier to see against a white backdrop."

cloud001 cloud002 cloud003

Sure enough! Monarchs were flooding southward on the strong north wind, blowing some 20+ mph. It took a minute or two to train my eye, then suddenly I saw them, zipping by as fast as the wind. I counted 86 monarchs in 5 minutes!

Discussion of Challenge Question #1
We asked, Even though they don't have the words to say it, what do monarchs instinctively know about time and direction?

Mrs. Lodge's science class from RHAM Middle School in Hebron, CT discussed the first challenge question and came through with shining colors. They say monarchs know that, "The sun appears to move across the southern part of the sky from east to west at a rate of 15 degrees/hour."

How to Respond to Today's Challenge Question
1. Address an e-mail message to:
2. In the Subject Line of the message write: Challenge Question #2 (or #3)
3. In the body of the message, answer the question above.

The Next Monarch Migration Update Will Be Posted on September 12, 2003.


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