Monarch Butterflies are in decline--they need your help to track where they gather

Monarch butterflies (Danaus plexippus) appear to be declining not just in North America but also in Australasia. Could this be a consequence of global change, including climate change, the intensification of agriculture, and urbanisation? We need more citizen scientists to monitor what is really going on.
Image: Monarch butterfly on New England Aster at Great Bay National Wildlife Refuge, Newington, NH. Credit: Greg Thompson/USFWS. CC2.0