Re: [SBB] Poorwill Status

[David Forthoffer <[[email protected]]>]

My information on the subject comes from Bernd Heinrich's excellent "Winter 
World". He has a chapter on Hibernating Birds. He mentioned one 
researcher's winter experience with a poorwill in 1947-1948 New Mexico: 
"Jaeger had measured the bird's internal temperature by inserting a 
thermo-probe into its cloaca. All his readings showed the bird's internal 
temperature hovered near that of the air temperature, as is usually the 
case when an animal is dead. He could detect no heartbeat with an aid of a 
medical stethoscope and saw no breathing movements of the chest. No 
moisture collected on a cold mirror held in front of the bird's nostrils. A 
flashlight shined a full minute into the bird's right eye (which was almost 
completely open) failed to elicit any response whatsoever. Jaeger 
concluded, 'I take it as evidence that the bird was in an exceedingly low 
state of metabolism, akin, if not actually identical with hibernation, as 
seen in mammals." Jaeger repeated this process five times over the course 
of 85 days, during which no or very few flying insects were seen in the 
Colorado Desert. The sixth time, Jaeger had just noticed many insects 
flying into his campfire and into the beams of his car headlights, and when 
he picked up that bird, it flew away out of his hand.

I do not know whether poorwills in our area hibernate. If they do, I 
suspect it is more related to food supply than to surviving cold temperatures.

David Forthoffer

P.S. Hello, Garth!

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