Wednesday, April 4, 2012

A Little Natural History

When I posted my photo of this butterfly yesterday, I didn't know anything about it.  Now I know a little and am quite intrigued.  First, I noticed there was still plenty of snow on the ground, and I wondered what a butterfly was doing out so early.  Second, I noticed that when approached quickly enough to scare it away, it would always come back and land in almost the exact same spot I'd scared it from. So, I did a little research.  First, I found a proper ID in the Laws Field Guide to the Sierra Nevada.  It's the Mourning Cloak, Nymphalis antiopa, Family Nymphalidae.  With that info, I searched the internet and read a half dozen or so articles which began to answer some of my questions.  It turns out this is one of the few butterflies that over-winters as an adult.  Also, the dark color enables it to absorb radiant energy more readily than lighter-colored butterflies, so it can get up to flying temperature even when the air is freezing.  The flight behavior has to do with its tendency to find choice perches and want to return to them, so long as the danger seems to have passed.  In other words, it wasn't attracted to me, but to its original landing place.  Lots more interesting lore and some unresolved questions await the curious.  By the way, once the butterfly returned from its circular flight and landed, I was able to get my camera within a foot of it without scaring it away again.  The place where I spotted this one was by a small creek crossing the Feather River College nature trail in a spot that had plenty of willows and cottonwoods where they like to lay their eggs.

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