Observing Monarchs in the Winter Sanctuaries
Comparing Clusters on a Branch

In the picture on the right, did you notice that:

  1. the sun is shining and
  2. the butterflies' wings are opened?

When the sun shines in the monarch sanctuaries, the butterflies open their wings to bask. It sounds like soft rain when thousands and thousands of wings move at once. If the butterflies get warm enough, they often burst into flight. This baffles scientists. If monarchs need to save their energy in order to survive the winter and migrate north in the spring, then why do they use so much energy to fly?

  • Further Reading: Field Notes from Mexico. Dr. Bill Calvert notices how the power of the sun affects butterfly behavior.

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