Here is another migration story, not fully understood. European eels seem to understand the Gulf Stream and drift will get their babies back home. Amazing.-http://www.sciencemag.org/cgi/content/abstract/325/5948/1660?sa_campaign=Email/toc/25-September-2009/10.1126/science.1178120-And a fascinating discussion of how the Monarch butterfly uses its antennae to to find an exact location in Mexico for its migration:- http://www.physorg.com/news173021625.html