Subject: overwintering butterflies

From: escott <[email-masked]>
Date: Sun, 28 Apr 1996 20:42:29 -0400

The Mourning Cloak (Nymphalis antiopa) and Compton's Tortoiseshell (N.
vau-album) were both equally abundant along the north shore of Lake Superior
last fall.  Today in Sleeping Giant Provincial Park, despite there being
still 2 feet of snow in the woods,  lots of butterflies were along the road,
which was virtually the only bare ground in the park.  These were mostly N.
vau-album and Polygonia species (P. faunus was the only one I identified
with certainty, when I pulled it off my truck radiator) in about equal
numbers, with only 2 N. antiopa, and one N. milberti.  The Compton's
outnumbered the Mourning Cloak by about 50 to 1.

I wonder if the relative scarcity of Mourning Cloaks could have anything to
do with its susceptibility to lethal freezing at -40C.  This past January
the temperature dropped below -40C for a couple of days.  Are the other
species hardier?

Or could most of the Mourning Cloaks still be under the snow?  Do they over-
winter closer to the ground than Compton's and P. faunus?  I guess I might
find this out in a couple of weeks when the last of the snow is (hopefully)
gone.

Any information on the overwintering biology of these species would be
appreciated.

Nick Escott
Thunder Bay Ontario
[email-masked]