Subject: Thermoregulation
Date: May 2 15:09:14 1995
From: Mike Patterson - mpatters at ednet1.osl.or.gov




Actually water is a very poor conductor of heat. It has a high heat
capicity. Changing the temperature of water requires lots of energy.
It is the combination of wet with air movement that causes high heat
loss. Bird legs in the water lose less heat than bird legs in the air.

One should also remember that a behavior properly defined is instinctive.
Standing on one leg may have adaptive significance in one part of the
environment (ie. cold places) and null significance in another. In
other words they do it out of habit. A way to test this hypothesis would be
to compared non migratory shorebirds to migratory shorebirds to see if
there are differences in one leg behaviors.

As to leg vascularization, shorebirds have a countercurrent mechanism
that reduces heat loss to the environment in the winter and dissapeates
heat in the summer. According to Gill's, _Ornithology_ this mechanism
is about 90% effiecient.



--
********************************
* Mike Patterson, Astoria, OR * "Time flies like an arrow;
* mpatters at ednet1.osl.or.gov * fruit flies like a banana."
******************************** - Groucho Marx