Intrigued by Tom Marko's description of a Song Sparrow in his yard 
apparently perspiring as he/she rushed around feeding Cowbird chicks, 
I turned as always to a trusted source for information on everything birdy:
Christopher Leahy's magnum opus, "The Birdwatcher's Companion to 
North American Birdlife," published by Princeton University Press in 
conjunction with the ABA.

I probably wouldn't possess this book but for the fact that the 
Editor of the ANS newspaper in Chevy Chase sent me a copy last year 
to review for the December 2004 issue.  I found it endlessly 
enjoyable and often pick it up just to read something at random.

Leahy confirms (page 810 of the 2004 edition) in the section on Body 
Temperature that birds lack the ability to sweat, which is of course 
the principal means by which we humans control body heat. (I should 
know, after an hour in the sun this morning, removing tons of weeds 
from the bank at the rear of our yard.)

Birds can try to control overheating by such means as increasing 
blood flow to certain parts of their bodies, compressing their body 
feathers, or in some species like cormorants, by vibrating the skin 
of the throat.  I also learned from Leahy that some vultures and 
storks cool off by defecating on their feet, with body heat then 
being used to evaporate off the moisture.  Fascinating!

Thanks to Tom and others who have reported interesting bird behavior 
in their back yards.  This is a great time of year to stay indoors if 
you can and observe the avian dramas occurring outside our kitchen windows.

Mike Bowen
Bethesda

D. H. Michael Bowen (Mike)
8609 Ewing Drive
Bethesda MD 20817-3845
Tel/Fax: (301) 530-5764
e-mail: