Monarchs overwinter in dense clusters on oyamel fir trees in Mexico, and their welfare during this vulnerable season is threatened by logging and climate change.
Monarchs during overwinter experience welfare challenges from exposure when forest canopy is reduced by logging. During severe storms, millions of butterflies are knocked from trees and die from cold and wet. Those that survive storms may be too depleted to complete spring migration. Habitat degradation forces higher clustering density, increasing disease transmission and knock-off risk during storms. Climate change is intensifying these storm events. The welfare of billions of individual butterflies depends on forest protection in this tiny geographic area.