Monarch Migration News: February 5, 2015
By Elizabeth Howard
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Your Sightings!
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Monarchs from across the continent are now clustered by the millions in a small region of Mexico. This year, half of the monarchs are concentrated in only one of the 12 overwintering sites.

Art Howard

Highlights: A Closer Look at Overwintering Monarchs
Seed Stock for Future
There are 57 million monarchs now overwintering in Mexico. The butterflies must survive 5 months of winter, migrate north in the spring, and then serve as the seed stock for future generations.

Half in One Sanctuary
Mexico's overwintering region includes 12 traditional wintering sites. Half of this year's butterflies are residing in only one site, the El Rosario sanctuary.

This means that half of our continent's migratory monarchs in Mexico are clustered together in an area the size of 1.5 football fields. The fact that the monarchs are so concentrated puts them at increased risk.

Compare Years
How does this year compare to previous years? These pie charts shows monarch distribution over 6 years. This column chart compares the number of monarchs per site per year. Notice how few sites the monarchs used: 80% of the monarchs were concentrated in only 1-4 sites.

Site Selection and Survival
Scientists don't fully understand what drives site selection. Some habitat variables include:

  • forest quality
  • available space
  • access to water
  • exposure to sun, moisture, wind
  • level of human disturbance

High quality habitat in Mexico is critical for monarch survival. Site selection comparisons guide conservation strategies and priorities.

57 Million
Estela Romero
Monarch Butterflies
Half in One
Monarch Butterflies
Compare Years
Conservation News

Webinar: Monarch Habitat Restoration
Coming February 12th: Step-by-step procedures for designing and managing native plant communities for monarch habitat.

Illinois Tollway Planting 286 Miles of Milkweed
The Illinois Tollway Authority this week agreed to work with the Natural Resources Defense Council to plant milkweed along 286 miles of roadways, including suburban areas of I90, I88 and I294.

Monarch Moves Toward Endangered Species Status
The U.S. Fish and Wildlife Service says that Endangered Species Act protection may be warranted for monarchs. The agency will now conduct a one-year status review.

How you can help monarch butterflies
Maps: Report Your Sightings
Monarch butterfly migration map Monarch butterfly migration map Map of milkweed emergence: Spring 2015
What to Report First Adult
report | map | list
report | map | list
Monarch butterfly migration map Monarch butterfly migration map Monarch butterfly migration map
First Egg
report | map | list
First Larvae
report | map | list
Other Observations
report | map | list
Journal and Activities
  • Slideshow: How Scientist Estimate Monarch Population
  • Journal: Where are the Monarchs?
Next Update February 12, 2015