QUESTION #1 How do the monarchs "know" when it's time to leave Mexico?
From NEW YORK: "We think that environmental factors play a big part in this. We think that they respond to the change in the temperature as well as to the amount of light during the day. We learned that many plants and animals respond to the amount of sunlight and day length. We think that this triggers their internal "clock" in some way." Mrs. Berger's Class K12ROBZJ@vaxd.hofstra.edu
From VIRGINIA: "To answer the challenge question about how the butterflies know how to leave Mexico, I thought like a butterfly. They know to leave when it gets to a certain temperature." Chris Scanlon "I believe the answer to the challenge is they know when to leave when they're able to feel a certain temperature. When I find it too hot in Virginia Beach, I go inside and butterflies need to travel when it gets too hot also. "Justin Merz odcwsk@pen.k12.va.us
From VERMONT: Sam: They leave when it is getting too hot. Jessica: They leave when it smells like spring. Ruby: It's like when we go to bed at night. We sleep for a certain amount of time then we wake up and we get up. The same thing happens with them. They sleep for a certain amount of time. Then they wake up and get up and they know that its time to come over here. Monique: Maybe when it gets too hot in Mexico, they know its time to come Cabot and other places in the north. Cabot, Vermont Cabot12@aol.com
From OREGON: Hi, We are the First Grade Class at St. John's School in Milwaukie, Oregon. We think the monarchs know when to leave Mexico by just using their senses or instincts. Mrs. Kennedy's 1st Grade Class, Milwaukie, Oregon, ELK53@aol.com
From MICHIGAN Dear Journey North, We are Mrs. Kennedy's Intermediate Class from Lewiston School in Lewiston, Michigan. We think Monarchs know the right time to leave Mexico because they lose their natural resource which is milkweed. The monarchs move on until they find a new source of milkweed. They also know by the weather. They move when it gets too hot or too cold. We enjoy talking about your Challenge Questions. It is fun to see how other classes answer them. Mrs. Kennedy's Class bkennedy@edcen.ehhs.cmich.edu
From MINNESOTA: Second graders in Miss Iffert's class in Eagle Lake, Mn had several suggestions for why monarchs "know" that it is time to leave Mexico. They are: the temperature getting warmer lets them know, instinct, and the presence of more people watching them in Mexico makes them want to leave. Lori Iffert, Second Grade Teacher, Eagle Lake Elementary liffer1@eagle.isd77.k12.mn.us
From NEW YORK: My 5th grade class in Hammondsport, N.Y. came up with some interesting hypotheses for how Monarch Butterflies know when to leave Mexico and head North. Group 1) We think that Monarch Butterflies sense a change in the temperature and that tells them when to begin migrating North. When the temp. begins to get warmer the Monarchs instinctively know it's time to begin their trip. Group 2) We think that Monarch Butterflies sense a change in the angle the sun's rays strike the Earth. When the sun begins to move North, so do the butterflies. Group 3) We believe that the length of the days tells the butterflies when it's time to head North. When the days begin to get longer, the butterflies know they should begin their migration North. Group 4) We think the butterflies react to changes in the humidity and that signals them that it is time to begin the journey north. My class plans to research other animals that migrate to see if other animal migrations might shed some light on this problem. Lee Westbrook's 5th grade class Hammondsport, N.Y. lwestbro@llwcny.ll.pbs.org
From MINNESOTA: How do you think the monarchs "know" when it's time for them to leave Mexico "When it is cold." Win Bennett "When its cold." Andrew_Barker Blake School Win_Bennett05@blake.pvt.k12.mn.us
Thanks for all the great answers. You're attempting to answer questions that don't have an answer yet! Congratulations to Mrs. Berger's class for seeing the connection between day length and migration. Scientists think the combination of warmer spring temperatures and lengthening photoperiod tell monarchs it's really spring. By using both cues, the monarchs aren't "fooled" by unseasonably warm weather in mid-winter. Congratulations also to Ruby of Cabot, Vermont for drawing on her own experience with sleeping cycles and concluding that butterflies have a "biological clock" that tells them it's time to go.
The next set of questions and answers concern North America's two monarch populations:
From MINNESOTA: Mr. Hatleli's second grade class from Eagle Lake Elementary school in Eagle Lake, Minnesota, USA has discussed the challenge questions about the monarch colonies. Here are our answers: Q. Why do you think there are two populations of monarch butterflies in North America? Answer: We think it is because of the mountain ranges that divide North America. Q. Why do you think there are over 150 monarch wintering sites in California but only 9 in Mexico? Answer: We weren't exactly sure, but we think that the weather and temperature are the reasons for this. jhatle1@eagle.isd77.k12.mn.us (Jim Hatleli)
From NEW YORK: Q. Why do you think there are over 150 monarch wintering sites in California but only 9 in Mexico?
A. First we believe that the climate and temperature of both places is similar which would make for a good winter site. There is also an abundance of milkweed in these places so the monarchs center there. The monarchs need to migrate to a place that is within a reasonable distance as they have to get there before they die. We think that the two sites of California and Mexico enable the monarchs of the surrounding areas to get there within that time period. If it were too far away, they couldn't make it. We think it is because there are better climatic conditions and less natural enemies in California. Mexico may have more creatures that prey on the monarch. Mrs. Berger's Class, Roslyn, NY" <K12ROBZJ@vaxc.hofstra.edu>
Great answers! The Rocky Mountains do form a physical barrier that divides the east and western monarch populations. Scientists don't know the exact dividing line between these populations. If you look at a good physical map of the Rocky Mountains you can see why. There are areas between the mountain ranges which might be accessible to monarchs from both populations. Scientists have conducted "transfer experiments" in attempt to learn more about monarch migration in these regions. This is somewhat controversial as will be discussed in a future report. After reading both sides of the issue you will be asked to vote and express your ideas about these experiments.
Why are there so many more monarch colonies in California than in central Mexico? The physical conditions along the west coast of California are humid and warm enough for monarchs to survive the winter in many places, over 150 in fact. In contrast, if you were to visit central Mexico you'd see that the ideal conditions for wintering monarchs are only found high in the mountains. There are very few mountains high enough, and with the right forest cover, to provide these conditions. When standing in the valleys below you can accurately point out the few mountain tops on which you'd expect the monarchs to be found. In most years, the temperatures in these valleys are too warm and dry for the monarchs to survive the winter.
How many is 60,000,000? Several schools responded to this question. You can illustrate their discoveries using an outline map of the U.S. states and/or Canadian provinces. Shade in the areas required to make a combined population of 60,000,000 people.
From PENNSYLVANIA: Dear Journey North Friends, We figured out how many states it would take to make up 60 million people, and it was more than anybody guessed. There are a LOT of monarchs in Mexico, aren't there!? (Actually, there WERE a lot in Mexico- now they are headed our way!) We started with our home state, Pennsylvania, and added states that touched Pennsylvania. Our final list was: Pennsylvania, New York, Maryland, Delaware, New Jersey, Connecticut, Rhode Island, Massachusetts, Maine, New Hampshire, and West Virginia- for a total of 60,144,384. Your friends in Pennsylvania, Mr. Roades' class Titus Elementary School hes00011@llpptn.ll. pbs.org
From ILLINOIS: The students from Cumberland School in DesPlaines, Illinois have been discovering just large the number 60 million really is. The fourth graders found out how many state populations it would take to make 60 million. Tom Young used the following states for a total number of 60,429,927 people: Illinois, Wisconsin, Iowa, North Dakota, Indiana, Maryland, Michigan, Missouri, Kentucky, Tennessee, Arkansas and Alabama. Erin Cruz used 10 states for a total population of 60,032,600. Erin used Mississippi, Illinois, Indiana, Iowa, Wisconsin, Missouri, Michigan, Kentucky, Minnesota and Ohio. The student were very surprised by their findings and enjoyed the puzzle. monarch@ais.net
From MINNESOTA: How many is 60,000,000? SD - 696,004, North D - 638,800, Iowa - 2,795,220 Minnesota - 4,375,099, Wisconson - 4,891,769, Michigan - 9,295,297, IL - 11,430,602, MO - 5,117,073 NE - 1,578,385, Kansas - 2,477,574, OH - 10,847,115 WY - 453,588 = Total 60,140,685 people 0227cvel@InforMNs.k12.MN.US
How Many Monarchs Per Student? Dr. Bill Calvert estimated the density at the over-wintering monarchs was 13,000,000 monarchs per hectare. If your classroom were packed with monarchs at the same density, how many would each student have?
From PENNSYLVANIA: Dear Journey North Friends, We got busy with our calculators to find out how many monarchs would be in our classroom, and how many there would be for each student, if they average 13 million per hectare in Mexico. First we had to find out what a hectare was. The dictionary said it was the same as 2.5 acres. Then we had to find out what an acre was. Again the dictionary said it was as big as 4840 square yards. We measured to find out what a square yard was. Next we measured our classroom and multiplied to get the area- 392 square feet. we found out that there would be 119 monarchs per square foot. That means we would have 46,648 monarchs in our classroom. Each student would have 7,775 butterflies! Your friends in Pennsylvania, Mr. Roades' class, Titus Elementary School hes00011@llpptn.ll.pbs.org
From WISCONSIN: Jason T. came up with this answer . There would be 107,900 butterflies in our classroom with 4,691 butterflies for each student. From: PLAEHNC@UWSTOUT.EDU
From MINNESOTA: Hectare = about 2 football fields (10,000 meters sq.) Our classroom is 21 x 27 feet (.0057 hectares) Would hold 228,070 Butterflies per person (21 students) 10,860 butterflies 0227cvel@InforMNs.k12.MN.US (Bill Van Loh/Sandy Sullivan)
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