Subject: Curious feeder behavior
Date: Mar 12 17:45:51 2003
From: Jerry Blinn - 76506.3100 at compuserve.com



<<<<<<<<<<<<<<<<<<<<<<<
>> That IS interesting. I pulled up a picture of the feeder on the
internet:
>> http://www.petluvers.com/perky-pethummingbirdfeeder.html
>>
>> It's a gravity feeder. Maybe the hummingbirds can sense the weight of
the
>> reservoir in the pressure they feel when they put their beaks into the
>> feeder. Perhaps they prefer the lower pressure of smaller reservoir.
Real
>> flowers don't "push" the nectar into the hummer.

>That's an interesting take on the gravity feeder theory. I had vaguely
>thought of that but guess I dismissed it since "pushing" the nectar didn't

>seem so much an issue since there is always nectar in the tube and the
>hummers just lap away at it with their little tongues going a zillion
miles
>per second. >>>>>>>>>>>>>>>>>>>>>>>>>>


Actually, with that feeder (and their 30 ounce feeder), there is
~no~ "pressure." The nectar in the feeding base simply sits there at
ambient air pressure. The feeder functions because of a partial vacuum at
the top of the bottle.

When the nectar level in the feeding base gets too low, the seal to the
nectar in the bottle is broken, air escapes, in a bubble, to the top of the
bottle, and nectar drops into the base until the seal is restored and the
partial vacuum in the top of the bottle returns to a negative pressure
balancing ambient air pressure.

Jerry Blinn
Placitas, NM
76506.3100 at compuserve.com


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