We were treated to a display that was simply astounding. When we entered the woods and descended, we saw the first hint of the orange patina of basking monarchs. The surrounding forest was full of butterflies that seemed to float on invisible winds rising through the high canopy. After walking 10 minutes into the forest we came upon the area where the main clusters remain. Millions upon millions were basking in the sun.
People always wonder how many butterflies they're actually seeing.
On the basis of that study we estimated 13,000,000 monarchs per hectare. Albeit crude, you can use that figure to estimate the total number of monarchs in a colony. To put the number into perspective, convert butterflies to people. When you visit the colonies late in the day, the forest floor and stems of under-story plants are often covered with shivering butterflies. Shivering is most pronounced when temperatures are low.