How Does the Forest “Shelter” the Butterflies?
To answer this question we must know something about the impact of vegetation and forest structure on microclimate.
of the Forest: Daily Temperatures Rise and Fall
the Forest: Daily Temperatures Are More Stable
So in the absence of intense tropical radiation outside, the forests remain cooler during the day, and at night warmer. Certain species of plants thrive in this microhabitat . These are adapted to supply nectar to monarch butterflies and in turn be pollinated by the masses of butterflies that inhabit the forests. The forest acts like a blanket retaining warmth during the cold nights and keeping out the heat during the day.
Temperature and also humidity variations are dampened; the extremes occurring in clearings are reduced within the forest, to the great benefit of the butterflies.
The high altitude forest of the transvolcanic belt of Mexico are extremely limited. (See map.) Overwintering monarch butterflies must have cool temperatures--but not freezing temperatures--and moist conditions--but not soggy ones. Thus, they have very limited habitat from which to choose.