Will climate change depose monarchs?

If Mexico gets too wet, migrating monarch butterflies could lose their winter refuges.

If you’ve ever seen a flock of migrating monarch butterflies, you’re one of the lucky ones. Fifty years from now, your memory might be all that’s left of the flapping beauties.

A computer analysis suggests that some monarch  populationss could die out in North America if the weather in Mexico changes.


Monarch butterflies’ winter homes in Mexico may become unsuitable as the climate changes and the risk of snow and ice increases.


Monarch butterflies fly great distances to spend their winters in warm places. Some of them spend their summers in the western United States and Canada. Later, they migrate to beaches in California during the winter. Monarchs east of the Rockies bask in the Mexican sun all winter. Some 200 million butterflies make the trip every year.

Karen Oberhauser works at the University of Minnesota at Minneapolis St. Paul. She and a colleague used a computer program to predict the future of January weather in the dozen or so places in Mexico where monarch butterflies usually go.

That program predicted that temperatures in the butterflies’ Mexican habitats would stay monarch-friendly. Precipitation, on the other hand, would more than triple by 2050. Monarch butterflies have never been known to survive in such wet conditions.

If the climate in Mexico changes as predicted, researchers hope that the butterflies will adapt. They might do this by finding other places to spend their winters. The research also shows just how challenging and uncertain life can be for animals that migrate so far each year.

Going Deeper:

Milius, Susan. 2003. Will climate change depose monarchs? Model predicts too-wet winter refuges. Science News 164(Nov. 15):310. Available at http://www.sciencenews.org/20031115/fob7.asp .

You can learn more about monarch butterfly migrations at www.learner.org/jnorth/fall2003/monarch/index.html (Annenberg/CPB).

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