Monarch Migration Update: March 25, 2010
Please Report
Your Sightings!

The migration is crossing Texas now and appears to be entering Louisiana. With numbers low this spring, everybody is wondering what it will take for the population to recover. How does a population grow? This week, learn about the monarch's reproductive potential and explore the factors that can limit the population's size.

This Week's Update Includes:

Image of the Week

First Steps

News: Enthusiasm Big, Numbers Small

Entering Texas
People called out with delight as monarchs appeared across southern Texas during the last week:

"A big, BEAUTIFUL, faded, gliding monarch floated through the backyard one hour ago!!!! Couldn't make out male/female. Wings were so faded it was almost colorless, as the sun shown through its wings but, without a doubt, a monarch," wrote Mrs. Baker, who teaches 3rd grade in Cypress, Texas.

The northernmost monarch has now reached latitude 33 N, according to our observers, and the migration appears to have entered Louisiana. In what state do you think the monarchs will appear next?

More Monarchs on the Way!
While visiting the overwintering sites in Mexico from Minnesota, Dave Kust and his daughter, Katie, witnessed much monarch activity. At midday on Monday, monarchs were flying by at an estimated rate of 280 per minute—and heading northward!

Sightings Down This Spring
As of March 23, we had received only 30 sightings! This compares to 125 sightings last spring at this time, to 74 sightings in 2008, and to 71 sightings in 2007. (See graph.)

Recovery—What Will it Take?
What do small numbers of monarchs coming up from Mexico mean for monarchs this spring, summer and beyond? Recovery of the monarch population is in the forefront of everyone's mind as we follow this spring's migration.

Monarch biologist Dr. Bill Calvert says recovery of the population depends on factors such as "temperatures and moisture in the breeding zones, the consequent conditions of the monarch food plant, the population levels of monarch parasites and predators—too many unknowns to predict with any certainty."

Dr. Chip Taylor of Monarch Watch says, "We have no prior experience with such a small returning population and it is uncertain whether monarchs in such numbers could recover in one year." He added, "My thinking now is that it will take monarchs at least two, and perhaps more, years to recover from the effects of the last breeding season and the winter of 2009-2010."

Eggs mean monarchs!
One way to watch for monarchs is to watch for monarch eggs. Check your milkweed regularly and you'll know when monarchs have arrived in your region.


Sightings are down!


The Migration: Maps and Journal Page



This year's small monarch population means spring sightings are especially important. Please help us document when and where monarchs and milkweed appear this spring.

Slideshow: From Eggs to Butterflies: How Does a Population Grow?

The monarch population could go from one butterfly to a billion in only four generations! This week's slideshow explores the limiting factors that govern the size of the monarch population. Invite students to identify and record limiting factors that may impact the size of the monarch population as they follow the migration live this spring. Why don't we go from one to one billion butterflies? Find out!

Research Question and Links: Explore!

This Week's Research Question: In what ways do monarch mothers depend on Mother Nature to raise their young?

Research for facts as you read:

Additional links to explore:


More Monarch Lessons and Teaching Ideas!

The Next Monarch Migration Update Will Be Posted on April 1, 2010.