If you visit the monarch colonies on a cool day, the forest floor will often be covered with butterflies. Right away, you’ll notice them moving in an unusual way, as this video clip shows:
Observations Lead to Questions
Cultivating Keen Observers
Scientific investigations typically begin with observations of something intriguing or baffling. In turn, observations inspire questions. As you observe the video clip, create a “What I Observe/What I Wonder” chart in your science journal. Work through the following categories of questions to inspire deeper levels of observation:
After Viewing the Video Clip
Did you guess that the butterflies were shivering? Did you notice how hard the monarchs were working to warm up their muscles? If you stayed to watch, a monarch might shiver this way for many hours, with rests in between, and only move a few meters.
Why Do Monarchs Shiver?
After such observations, scientists have learned that shivering butterflies are too cold to fly — or even crawl. Butterflies littering the forest have usually been forced down by strong wind, rain, hail or even snow. At 10,000 feet in elevation, the over-wintering sites are often cold. Temperature in the sanctuaries can sometimes drop to zero C or even a few degrees below zero. Monarchs are paralyzed by temperatures this cold!
Try This! Shivering Simulation
Find a volunteer who's willing to shiver. Ask him to sit on the edge of his chair and shiver all the muscles in his body at once: arms, legs, feet, and hands. How many seconds does it take until he can feel his body warming? How long until he can feel himself getting tired? How long until he begins to perspire?
Why Stay Off of the Ground?
Challenge Question #9
As you can see, shivering uses energy. Now remember, the monarchs need to save energy in order to survive the winter and to fly back north in the spring.
National Science Education Standards