A Vanishing Migration

ex-monarch_python_002

Published in the November 2014 issues of National Geographic magazine

Fewer monarch butterflies are crossing North America to winter in Mexico, says the World Wildlife Fund Mexico. In 2004 an estimated 550 million completed the winter migration; last season an estimated 33 million made it, according to the fund’s count. Although illegal deforestation and severe weather contributed to the decline, recent research suggests that the biggest culprit is farms’ large-scale use of herbicides that destroy milkweed. Monarch caterpillars need to feed on the plant—but it decreased 21 percent in the United States between 1995 and 2013. That doesn’t bode well for the butterflies, whose life span is so short that those making the next migration will be the great-grandchildren of the previous migrators. For this winged orange icon, survival is a group effort.

—Lindsay N. Smith

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s