Photo of the Day 5 May 2008

Migrating Monarchs, El Rosario Preserve, Mexico, 2004
Photograph by Peter Essick

A colony of monarch butterflies clings to a tree in the El Rosario Monarch Butterfly Preserve in the mountains of central Mexico. The Mexican government is working to encourage tourism and discourage illegal logging in the preserve, where millions of these delicate orange-and-black butterflies come to nest each winter.