Monarch Migration News: March 3, 2016
By Elizabeth Howard

Inspired by the monarch population rebound, people are celebrating the good news and continuing with conservation efforts. What caused the increase?

Monarch Butterflies in Mexico
A Time for Celebration! Photo by Heather Jersild

Good News from Mexico: Population Rebound
The number of monarchs overwintering in Mexico has more than tripled from last winter's level and has increased dramatically from the record lows of the past 3 years. The clustering butterflies cover 4.01 hectares of forest. The population contains 200 million monarchs compared to a long-term average of 300 million and a peak of 1 billion.

Why the Increase?
Favorable breeding conditions in summer 2015 are credited for the population increase according to Dr. Karen Oberhauser of the Monarch Joint Venture.

"Good weather in the growing season this year allowed us to produce about the maximum number of monarchs as possible from the habitat we have, but we know that this amount of habitat can also produce many fewer monarchs in a bad year. All we need to do is look back to 2013 when approximately the same amount of habitat produced less than one hectare of occupied forest in Mexico. This suggests more habitat is needed to reach our goal of 6 hectares."

Goal is 6 Hectares
The target for monarch recovery is a sustained population of 6 hectares. The level must be high enough so that the population's natural yearly fluctuations don't drop below an extinction threshold. For long-term viability, the population must be resilient during conditions in an off-year.

"I'm ecstatic to see the increase, but cautious that it is still low by historic standards, and virtually equal to 2011, which dipped again afterwards. So... let's celebrate and then continue our efforts!" said Kit Goodwin.

Get Ready for Monarchs
The first signs of migration are expected any time. Welcome the monarchs back to the breeding grounds for the 2016 season with the flowers and milkweed they'll need to produce a new generation.

"I'm doubling up my milkweed garden this spring. If everyone did, maybe we'd have 8+ hectares next winter," tweeted Keith Chasteen from Kentucky.

Monarch butterfly population in Mexico: Chart
Population Up

Map Showing Distribution of Monarch Butterflies between the 12 Major Sanctuaries in Mexico
Evenly Distributed?
Which of the 12 major monarch sanctuaries in Mexico have the butterflies selected in the past? Pie Chart
Same Each Year?
How many millions of monarch butterflies in Mexico?
How Many Millions?
How the Population is Measured

What does the graph reveal about the monarch population?

Journal Page and Weekly Journal

Monarch butterfly population in Mexico: Chart
Maps: Report Your Sightings
Monarch butterfly migration map Monarch butterfly migration map Map of milkweed emergence: Spring 2016
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
Next Update March 10, 2016