Monarch Migration Update: April 18, 2013
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Your Sightings!
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Are monarchs traveling when and where their needs for food can be met? This week, explore the connection between nectar and migration.

This Week's Update Includes:

Image of the Week
Monarch butterfly nectaring
Got Nectar?

Image: Frank Matheson

News: Fresh Wings!
Fresh-winged monarchs have been spotted. These may be offspring of migrants from Mexico, so monarchs of the first spring generation:

"The eggs found mid-last month have resulted in some fresh wings in the past few days. It's great to see their bright colors." Chuck Patterson, Driftwood, Texas (April 14)

Cold Holding Them Back
The leading edge of the migration has not advanced beyond its position last week. A mid-continent cold air mass continues to hold the monarchs back. The northernmost sighting remains at latitude 37N. South of that line, monarchs seem to be stacking up. Many people in Texas reported multiple monarchs last week. Let's see what happens when the Great Plains warm up!

Surprise Sightings in the East
Meanwhile, amid warmer temperatures in the mid-Atlantic region came two unexpected sightings. First monarchs were reported from North Carolina and Virginia this week. Where do you think the monarchs came from?

Spring Green-up
Check out the milkweed map. Spring green-up has advanced to latitude 40N along Atlantic coast. In contrast, mid-continent milkweed has only emerged to latitude 37N; it's about 180 miles behind that in the east.

Monarch butterfly in Tamaulipas
Fresh Wings!
Image: Chuck Patterson

Monarch butterfly in Tamaulipas
Mid-continent Cold
Animated Map: Milkweed Emergence Spring 2011 vs. 2012
Surprise Sightings

Explore: Nectar and Migration
Adult monarchs eat nectar. By monitoring the availability of nectar-producing flowers during spring migration, we can study how closely the two events are ecologically matched.


Nectar and Migration
Photo: Susan Matthews

The Migration: Maps and Journal
  • Please report your monarch and milkweed sightings.
Monarch butterfly migration map Map of milkweed emergence: Spring 2013 Journal: Nectar and Migration

(map | animation | sightings)
(map | animation | sightings)
Next update April 25, 2013