Subject: Snow and adult hibernators

From: Kenelm Philip <[email-masked]>
Date: Tue, 26 Mar 1996 03:18:18 -0900

Dick Walton wondered if there was any research indicating that
adult hibernators have increased survivability following heavy snows. I
do not off-hand know any reason why a _heavy_ snow would be better than
an average snowfall--but at least in Alaska there are reasons why an
unusually light snowfall would lead to _lower_ survivability. Some years
ago I was involved in a project to determine the supercooling temperature
of the Mourning Cloak (_Nymphalis antiopa_). The temperature at which
they froze was around -40 (F and C)--at which point they were killed.
        The air temperatures in Fairbanks can run as low as -60F, and
usually dip below -40 each winter. Without a sufficiently thick insulating
blanket of snow, the overwintering adults will freeze.
        I have no idea whether the degree of cryoprotection is the same
in Massachusetts. If it is, it wouldn't take any snow to provide protection
against freezing! But if the degree of cryoprotection is less, then the
presence of sufficient snow may still be important.

                                                        Ken Philip
[email-masked]

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From: Dale Clark <[email-masked]>
Date: Tue, 26 Mar 1996 16:27:37 -0500

Dick Walton was wondering about the relationship of a heavy snowfall and
colder winter on the survival rate of Mourning Cloaks.  It would seemt o me
that milder winters, when there are many days throughout the season when the
hibernators can fly about and burn up stored fats and energy, would leave
some individuals "running out of juice" before spring and the sap flows
arrived.  So if it was a particularly rough winter (as it was this year) then
they would be forced to spend more time slumbering away in the relative
safety of their hibernating spots and thereby conserving energy.

Dale Clark