#Monarch #Butterfly In ‘Grave #Danger’ Of Disappearing, Migration Reaches Record Low But over the years, the Monarchs’ numbers have declined. Researchers from the World Wildlife Fund, who have studied the annual Monarch migration since 1993, say several factors have contributed to the butterfly’s disappearance. The biggest influences are loss of habitat and reduction of milkweed, the Monarchs’ primary food source, along North America’s western shores. &neo 2014-02-02 14:17:23 |