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Compare and Contrast
Monarch and Hummingbird Migrations

Running the Risks of Arriving Early
See-saw temperatures and the kind of winds that carried Dorothy to Oz are typical at this time of year. Earth is in transition between winter and summer; one day there's snow and the next there's sweltering heat. What happens to monarchs in changing conditions like these? What are the risks of moving north too quickly and arriving early? Look for examples in this week's update.

Dr. Brower Finds Frozen Milkweed in Florida
During last week's cold snap, temperatures dropped below freezing as far south as Florida. At Dr. Lincoln Brower's study site there, he observed the effect of the cold. He says that frost damage to milkweed is a hazard monarchs face in the spring. When monarch eggs hatch on damaged plants, the larvae will die of starvation.

• Dr Brower Finds Frozen Milkweed in Florida

Milkweed With a Dozen Eggs in Tennessee
"We sighted a monarch laying eggs on the few sprigs of milkweed that have come up in our butterfly garden. One cluster had at least a dozen eggs on it!"

This behavior is called "egg loading" (see photo). Egg loading is a sign that milkweed is in short supply. If milkweed were plentiful, monarchs would not lay so many eggs on a single plant. Hypothesize: why could egg loading be a problem for the larvae when they hatch?

The Migration Advances Northward and Eastward
The monarchs moved into four news states during the past week, advancing northward one degree latitude into Kansas and as far east as Georgia and South Carolina.

• Where will they go next? Record your predictions!

Last Friday, April 9th was one of the biggest days of the season. Sightings suddenly appeared on the migration map in Alabama, Georia, South Carolina, and Tennesse. Students at two different schools in Nashville were among the first to report monarchs in their state:

"We were playing on the playground at school when a Monarch sailed past. It went straight to our butterfly garden. We have been watching for them to return! We are excited to see them again. Our milkweed came up 2 days ago. Maybe the butterfly will lay eggs!" wrote David Lipscomb Elementary.

"We were out at recess and sighted the monarch in our playground," reported Glendale Spanish Immersion.

Questions About Sightings on the East Coast
Every year at this time sightings from the East Coast raise some interesting questions: Did those monarchs came up from Mexico or are they monarchs that overwintered on the coast? This is one of the unanswered questions about monarch migration and a question that citizen scientists can help to answer.

Photo: Kevin Turner
Monarch with a torn wing in Georgia

Photo: Nancy Garden
Milkweed with a dozen eggs in Tennessee

Freezing temperatures dipping as far south as Florida last week.

What happens in the spring to monarchs that overwintered on the coasts? >>