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Animal migration presents marvelous examples of good design:  how do many creatures find their way to their destination?

Animal migration presents marvelous examples of good design:  how do many creatures find their way to their destination?

Each year, a few towns in [[California]] are greeted by the arrival of tens of thousands of [[monarch butterfly|monarch butterflies]]. [[Pacific Grove]], California, is the peculiar destination of a huge quantity of such butterflies each year.

Each year, a few towns in [[California]] are greeted by the arrival of tens of thousands of [[monarch butterfly|monarch butterflies]]. Pacific Grove, California, is the peculiar destination of a huge quantity of such butterflies each year.

The [[PBS|Public Broadcasting Service]] provides a description of the phenomenon.<ref>http://www.pbs.org/wnet/nature/alienempire/voyagers.html</ref>

[[PBS]] provides a description of the phenomenon.<ref>http://www.pbs.org/wnet/nature/alienempire/voyagers.html</ref>

This report notes that one butterfly was tracked along a 1,870 mile route, from [[Ontario]] to [[Mexico]].  Its actual flight distance could easily have been two or even three times greater, because butterflies do not fly in straight lines.

This report notes that one butterfly was tracked along a 1,870 mile route, from [[Ontario]] to [[Mexico]].  Its actual flight distance could easily have been two or even three times greater, because butterflies do not fly in straight lines.