The
Monarch's Journey NORTH?
Analyzing
Spring Monarch Migration Patterns
Background
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How far from
Mexico — and in what direction — does the monarch migration
advance in the spring?
Imagine drawing the leading edge of the migration at different stages
as the monarchs move across the Continent. Such a line is called an "isopleth".
("Isopleth: A line on a map connecting points at which a given variable
has a specified, constant value." The "given variable"
would be "FIRST Monarch" and your "constant value"
must be a certain date.) Using this spring's monarch data, you can draw
the wave (an isopleth) at regular time intervals to show the migration's
advance.
Activity
- On the
map above, look at the color-coded key we use to show the date each
monarch was seen. Notice that the colors change every two weeks. (Click
on face of map to enlarge.)
- Print
a color copy of migration map.
- First
draw a line to show how far the migration had progressed by March 15.
To do this, connect those white
dots that are the farthest from the Mexican sanctuaries.
- How far
had the monarchs progressed two weeks later? Chose a different color
marker and connect those yellow
dots that are the farthest from Mexican sanctuaries. This lines
shows how far the migration had moved as by March 28.
- Every
two weeks, when the color changes, print out a new monarch migration
map. Chose a new color marker to draw the line of advance. For
each changing color, connect those dots that are the farthest from Mexican
sanctuaries. Save these maps, because it gets difficult to see
the waves when more sightings are added. Keep notes about your thoughts
on the back of each map.
- Consider the factors that might influence the migration. Draw upon other resources, such as weather, climate and vegetation maps.
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7. Finally, at the end of the season, summarize all the changes you saw.
Discussion Questions
- Describe the pattern you noticed every two weeks. In what ways did the pattern change during the spring season?
- Does the monarch migration truly move northward? Explain what direction(s) the monarchs moved and why you think this was so.
- How would you fill in the blank? "The spring monarch migration advances at the average rate of about ___ miles per week."
- Why is it so important to take into consideration the distance the monarchs have flown from Mexico when you analyze the pattern?
- What made this study difficult? How would you change it if you were to do it again?
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