You really think they are thick leaves on the eucalyptus trees then something flutters or the sun peeks through the branches and you are in wonder..some are on the ground, some fluttering and there are so MANY! This is a nice place to be anyway as it is near the ocean..high above the beach....I was thrilled when my son and his family came at Christmas and I could take them to see this beauty...
They migrate from Canada to Mexico..Some stay in California.
http://mamba.bio.uci.edu/~pjbryant/biodiv/lepidopt/danaidae/monarchm.htm
Scroll down for examples of how thick they are.(Mexico)
Great Link! Pix & Info.. thanks Meg.. out for a bit..