Numbers dwindle at Mexico's mountain of butterflies

Decline of Monarch population wintering in Mexico now marks a statistical long-term trend, experts say

This story was published in January, 2014

The number of Monarch butterflies (Danaus plexippus)wintering in Mexico plunged this year to its lowest level since studies began in 1993, leading experts to announce Wednesday that the insects' annual migration from the United States and Canada is in danger of disappearing.

A study released by the World Wildlife Fund, Mexico's Environment Department and the Natural Protected Areas Commission blames the displacement of the milkweed the species feeds on by genetically modified crops and urban sprawl in the United States, as well as the dramatic reduction of the butterflies' habitat in Mexico due to illegal logging of the trees they depend on for shelter.