In the Mexican MountainsButterflies in Mexico

Join us on Tuesday, February 17, 2009 for a webcast and broadcast from Sierra Chincua, one of only a few mountain peaks in the Mexican states of Mexico and Michoacan in which monarch butterflies overwinter.  This is the first time that a live television program or webcast has come live from the Monarch Butterfly Biosphere Reserve.

The eastern population of North America’s monarchs overwinters in the same Mexican mountain areas every year from October to late March. Monarchs roost for the winter in oyamel fir forests at an elevation of 2400 to 3600 meters (nearly two miles above sea level). The mountain hillsides of the oyamel forest provide an ideal microclimate for the butterflies. Here temperatures range from 0 to 15 degrees Celsius. If the temperature is lower, the monarchs are forced to use their fat reserves. The humidity in the oyamel forest assures the monarchs won’t dry out allowing them to conserve their energy.

Directional Aids

Researchers are still investigating what directional aids monarchs use to find their overwintering location. It appears to be a combination of directional aids such as the magnetic pull of the earth and the position of the sun among others, not one in particular.

Protection of Oyamel Forest

Conservation of overwintering habitat is very important to the survival of monarchs. In 1986, the Mexican Government recognized the importance of oyamel forests to monarch butterflies and created the Monarch Butterfly Biosphere Reserve. In July 2008, the Monarch Butterfly Biosphere Reserve was named a World Heritage site by the United Nations Educational, Scientific and Cultural Organization (UNESCO).  

This information was summarized from:

During the webcast and broadcast on Tuesday, February 17, 2009, from noon to 1 p.m. Eastern Time, learn about:

  • How monarch butterflies can withstand the cold mountain climate in the Mexican mountains.
  • How population counts of the wintering monarch population are carried out.
  • An overview of the ideal conditions in the oyamel fir forests for monarch topor
  • Finding and reporting tagged monarchs in the Mexican forests
  • Conservation work in Mexico by the World Wildlife Fund

Here's how you can participate:

  • Watch the webcast and broadcast on Tuesday, February 17 from noon – 1 p.m. Eastern Time. The webcast will also be archived for later viewing if you can’t watch it live.
  • Check out the lesson plans and links.
  • Watch the short video segments.
  • Take a Google Earth tour.


For more information about monarchs’ winter destination in the Mexican mountains, visit the following web pages:

Monarch Butterfly: North America’s Migrating Insect
The eastern population of North America’s monarchs overwinters in the same 11 to 12 mountain areas in the States of Mexico and Michoacan from October to late March.

Journey North
Journey North has information about monarach’s overwintering season.