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Re: Extinction

tlcomp@iu.net suggested a kind of hibernation, or estivation, for

>[snipped] or go into a kind of suspended animation, slowing metabolic 
>rate down drastically to survive at night when they're not feeding.  
>Hummingbirds do this and probably other birds as well.  It would seem 
>plausible that if a major impact caused a 'nuclear winter'-type  effect, 
>then those animals who were tricked into thinking it was night or winter, 
>and went to sleep, survived.  We don't know very much about the specific 
>triggers that cause animals to go into hibernation now, so this will 
>probably remain just conjecture.  What think all?    Marty Loss   

Not sure about details in birds, but in temperate-zone bats the
ability to hibernate is strictly seasonal, and pretty closely timed in
terms of how long they can survive without going out and getting more
food.  E.g. Myotis lucifugus, which can withstand near-freezing body
temperatures during winter hibernation, dies if its body temperature
falls anywhere near that in summer.  And bats which are repeatedly
disturbed during hibernation frequently die of starvation, since
waking up uses large quantities of stored fat.  (Daily torpor during
the summer is much less drastic, with less change in metabolism, at
least for bats.)  So this method probably wouldn't help much for
anything with a bat-like metabolism, anyway, unless the catastrophe
happened during winter, and didn't last too long.  And winter only
affects part of the planet at a time, whereas the K-T extinction seems
to have been pretty general.

Anyone have comparative information on snake hibernation, etc., to offer?

--  Pat Grant                               patg@vax2.concordia.ca  --