Migration Update: April 9, 2009
Please Report
Winter Sightings! >>

Today's Report Includes:

 


Dr. Lincoln Brower, Sweet Briar College

What is this? >>

The Migration: Highlights, Maps, and Questions

Monarchs
(map/sightings)

Milkweed
(map/sightings)


Journal Page
Why is the Migration Moving Northeast?

Highlights: The Stop-and-Go Nature of Monarch Migration
The monarchs made a clear push into Oklahoma and Arkansas during the past week. A strong south wind blew on Saturday and that single day was responsible for the week's biggest push. Watch the animated migration map and you can see the jump.

The cause of last week's stop-and-go migration were two cold fronts with a short break in between, when a warm front and south winds allowed the monarchs to make some progress. You can see the location of Saturday's warm front and south winds on the maps to the right.

The migration entered only one new state last week. (Can you find it?) This illustrates how little the migration advanced; instead, the butterflies were filling in behind the migration's leading edge. Remember, our map shows where observers saw the first monarchs of spring. Following behind is a parade of monarchs, millions strong and at least 1,500 miles long. (Last Wednesday Estela Romero reported that there were still thousands of monarchs at one of the sanctuaries as you'll read below.)


Field Reports from Citizen Scientists: Who saw...?
Who saw monarchs with fresh wings and why is this significant? At what latitude are monarchs arriving where the milkweed is just emerging, and what does that mean?

Weather on April 4th

Notice how the warm front stretched northward from Texas and into Oklahoma on Saturday, where migration-watching was spectacular.

In the region below the warm front strong south winds were blowing on Saturday.

 

Record your predictions!

Hypothesize! Which Way is the Migration Moving — and Why?

This is a fascinating time of the migration. Notice how far east the monarchs have gone and how little they have moved to the north. Look carefully at the migration map and find the overwintering sites in Mexico at longitude 100 West. If the migration were traveling directly north the monarchs' path would follow 100 W. What's causing the monarchs to travel where they are? Before reading on, write in your journal:

Why go northeast? >> Explore climate and migration! >>

The orange arc on this map shows where monarchs would be now if they had spread equally in all directions. Why do they advance most quickly to the northeast at this time of year?

What effect do temperatures have on the pace and direction of migration? Here are migration and temperature maps over five years for you to compare. Take a look! Compare this year to past years.

News from Mexico: Some Still at Sanctuaries on April 1st >>

"I was curious to see how many monarchs remained up in the sanctuaries so I took a trip up to El Rosario," wrote Estela Romero last Wednesday. Here are her photos and observations.

Spring_LaSalud040109_3

Please Report Your Sightings!

Links: Monarch Butterfly Resources to Explore
More Monarch Lessons and Teaching Ideas!

The Next Monarch Migration Update Will Be Posted on April 16, 2009.