Monarch Migration Update: April 4, 2013
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Your Sightings!
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Cool temperatures are holding back milkweed and monarchs. Is the migration later than normal? Explore historic records to see what long-term data reveal.

This Week's Update Includes:

Image of the Week
Monarch caterpillars on milkweed leaf.
Got Milkweed?
Photo: Elizabeth Howard
News: Concentrated in Texas
The migration has hardly moved out of Texas. Over 80% of this spring's sightings have occurred there so far. The concentration of monarchs in Texas highlights that state's importance to the population. The size of the next generation will be largely determined by the quality of spring habitat in Texas.

The Final Month
By the end of April, most monarchs migrating from Mexico will have reached the end of their lives. Watch where monarchs travel during April to see where other spring breeding habitat is located.

A Dramatic Difference from 2012
Spring 2012 was the warmest on record. Milkweed had already emerged 800 miles north of today's northernmost sites. Minnesota and Ontario had reported milkweed by early April 2012! This spring's temperatures and rate of spring green-up are closer to normal.

Milkweed and Migration Synchronized
Milkweed emergence and monarch migration are closely synchronized. Compare migration patterns of last spring to this spring. Notice the similarity between the migration and milkweed maps each spring.

Monarchs and Temperatures
Temperatures affect monarchs throughout their annual cycle. Think about examples during spring migration, the breeding season, fall migration, and overwintering period.

Monarch butterfly with faded wingsin Texas
Time is Passing
Photo: Chuck Patterson
Animated Map: Milkweed Emergence Spring 2011 vs. 2012
Milkweed and Temps
Monarch butterfly eggs on newly emerged milkweed
Milkweed and Migration
Photo: Debra Barnes

Explore: Historic Data
Is the migration later than normal this spring? Explore historic records to see what long-term data reveal.


Monarch butterfly in Tamaulipas
Arkansas Example
The Migration: Maps and Journal
  • Please report your monarch and milkweed sightings.
Monarch butterfly migration map Map of milkweed emergence: Spring 2013 Journal Page
(map | animation | sightings)
(map | animation | sightings)
Next update April 11, 2013