You know, Rod, this is what I find astonishing about the Monarch migration: It is multigenerational. The ones that begin aren't the ones that finish the journey. How???
The Monarchs I looked at closely this spring all had perfect scales and perfect wingtips. Pretty sure they were a post-winter generation.
They each came out of their chrysalis alone, how did they know they were supposed to fly towards Canada after their wings dried?