Predators avoid monarchs because they've learned they taste bad.
Monarchs use bright coloration in their wings to warn their predators that they're poisonous. Millions of monarch butterflies spend the winter in just a few overwintering sites in the mountains in central Mexico, in the states of Michoacan and Mexico. Human activity poses a great threat to the monarch, particularly as deforestation destroys necessary habitat. Scientists believe that the monarchs use the position of the sun and the earth's magnetic field to guide them to their destination. Hundreds of thousands of kids in Canada, the U.S. and Mexico participate in monarch observation and conservation activities every year.