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Inestimable Numbers of Monarchs Die in Mexico

© Naomi Mathews

The phenomenal 3,000-mile fall migration of hundreds of millions of Monarch butterflies from northern United States and southern Canada to their overwintering grounds in Western Mexico continues to remain a complete mystery to scientists. You can read about this incredible journey these butterflies make annually in one of my previous articles, The Mystic Fall Migration of North American Monarchs , (October 1999). This article also outlines the four different life stages of the Monarch butterfly (Danaus plexippus), and also how butterfly gardeners can attract these beautiful "flying flowers" to their gardens.

Another informative article, Monarchs' Winter Habitat Loss Looms in Mexico, (October, 2000), touches on the grave concern of conservationists and other Monarch butterfly experts regarding the degradation of conserved areas of forests in Mexico where Monarchs have overwintered for millenniums. This article also outlines how a team of concerned international groups is working together toward solving this crisis.

Although Monarch butterflies are not an endangered species, they do face many "dangers" during their brief life span. For example, many are destroyed by predators on their long journey to Mexico; others may starve to death for lack of nectar; some may die of disease; still others perish after imbibing nectar from flowers treated with poisonous pesticides. In spite of these dangers, the large majority of these migrating Monarchs do survive and reach their destination to the Oyamel forests in Mexico in the fall of every year.

There is, however, a more unpredictable and sinister danger that Monarchs and all species of butterflies face, and that is the adverse forces of Mother Nature. Butterflies are cold-blooded insects that cannot survive in severe cold temperatures -- especially freezing temperatures.

Unfortunately, in mid-January this year (2002), an unusually severe winter storm dumped several inches of rain on two of the largest colonies of overwintering Monarchs in Mexico -- Sierra Chincua and El Rosario. These two colonies are located in the mountains west of Mexico City in the state of Michoacan. Following the heavy rains, the temperature dipped down to freezing levels -- the lowest temperature recorded in 25 years. On February 27, 2002, an article in the New York Times reported that the devastating result of this storm was the massive demise of between 220 million to 270 million beautiful Monarch butterflies.

Those millions of soaking wet Monarch butterflies simply froze to death in thick, massive clusters. Their usual warm and protective overwintering grounds to which they had traveled so far became their final resting place. To view some incredible photographs that were taken by the World Wildlife Fund of the masses of Monarchs that perished during this storm, click on the following links: