Monarch butterfly refuge

I traveled to the El Rosario Monarch Butterfly Refuge in Mexico. It was an exhausting journey but the butterflies were so amazing. Millions of them were hanging in the trees, flying through the air, mating and dying. One of those once-in-a-lifetime experiences with images you will never forget.
Soon they will begin their journey back up into the United States and Canada. The monarchs are endangered by loss of habitat and herbibcides that kill the milkweed their caterpillars feed on. These amazing creatures were able to survive the last ice age, but they may not survive us.