Mexico’s Monarch Butterfly Population at All-Time Low

By John Mitchell

According to a census taken by World Wildlife Fund – Mexico, the number of monarch butterflies wintering in Mexico has fallen to the lowest on record.

Every autumn, tens of millions of monarch butterflies migrate from as far away as eastern Canada to the states of Mexico and Michoacan. Here, they hibernate in the mountainous terrain, coating the oyamel fir trees in brilliant orange blankets. When air temperatures warm in the spring, they begin the long journey back to their northern breeding grounds.

Hibernating butterflies blanket the branches of a tree in the El Rosario Monarch Butterfly Sanctuary, Michoacan, Mexico. Click on image to view usage info.
Hibernating butterflies blanket the branches of a tree in the El Rosario Monarch Butterfly Sanctuary, Michoacan, Mexico. Click on image to view usage info.

The recent drop in the number of monarch butterflies over-wintering in Mexico is being blamed mainly on drought plus abnormally high and low temperatures in parts of North America where the monarchs reproduce. Also, the insects’ Mexican habitat continues to be illegally deforested in order to harvest valuable timber and clear land for agriculture.

Although scientists say that the monarch butterflies are not in danger of extinction, they think that their declining numbers may threaten the annual migration to Mexico.

Mexico has four monarch butterfly sanctuaries in Michoacan and the Estado de Mexico. They were designated a UNESCO World Heritage Site in 2008 and now comprise the 56,259 hectare (about 139,00 acres) Monarch Butterfly Biosphere Reserve.

Hikers in the El Rosario Monarch Butterfly Sanctuary, Michoacan, Mexico. Click on image to view usage info.
Hikers in the El Rosario Monarch Butterfly Sanctuary, Michoacan, Mexico. Click on image to view usage info.

For tourist information on Mexico’s monarch butterfly sanctuaries, visit the WWF-Mexico website.

2 thoughts on “Mexico’s Monarch Butterfly Population at All-Time Low”

  1. It is also important to think of the habitat of Monarchs in North America. The various species of Milkweed,their larva food are impacted by development, agriculture and the desire for lawns rather than wildlife supporting yards, In addition, forms of insecticide and the BT in corn products that may kill monarch larva

    I encourage all who are fascinated by these small bugs and their lifecycle to encourage communities not ot mow in vacant lots and along side roadsides, replant your yards with milkweed and nectar producing native plants and to teach your community members, city administration, street departments and schools of the opportunity to support and learn from this phenomena.

  2. Some very good suggestions, Loraine. Milkweed is crucial to the survival of the monarchs. I would also like to recommend an excellent book to anyone interested in learning more about the annual monarch butterfly migration to Mexico: FOUR WINGS AND A PRAYER by Sue Halpern.

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